Nitro Engines, Parts 1 and 2

[00:00:10] Cplane lab a podcast for anyone interested in rc airplane we'll share tips and tricks on how to build models and talk about successful flights epic crashes and everything in between visit us at rcplane lab.com to sign up for our email list and to ask us questions you can also text us or leave us a voicemail at 818-351-9846 please help us out by rating and reviewing us in your favorite podcast app thanks for spending time with us today now here are your hosts ron and tom hello

[00:00:38] Everyone welcome to the rc plane lab podcast i'm ron and i'm tom on today's episode we're going to be talking about nitro engines or glow engines my favorite yeah i know right i figured you'll

[00:00:52] You'll be doing a lot of talking in this one so yeah i'm i'm pretty long-winded so

[00:00:59] Buckle up folks that's okay we'll see what we get out of it and we'll we'll go from there okay so basics of a nitro engine it's kind of like like a diesel engine it has a glow plug that ignites the the fuel air mixture in the cylinder unlike a gas engine it doesn't have a spark plug so it's they're easier to install in in an airplane than a gas engine you don't have to have a separate battery to run your ignition all the time gosh what else

[00:01:34] Well that's about it for me so go on let me know well yeah yeah so so the majority of our

[00:01:44] Nitro model engines are two stroke but the four strokes are out there as well and the big the big differences between them is how they how they accomplish those four functions that all internal combustions have which is the suck squeeze bang and blow which is i've never heard it put that way yeah yeah you have to you have to suck so you have to pull the air fuel mixture into the combustion chamber and then you have to squeeze it you have

[00:02:15] To compress it and then bang you have to ignite it somehow and then blow you have to get the get the spent exhaust gases out of that chamber i like that that's pretty good heck my dad may have even taught me that a long time ago that's fine but yeah so a two-stroke we'll start there since the since those are by far the majority of the model engines out there a two-stroke accomplishes all four of those operations in one complete revolution of the crankshaft which is two strokes a downstroke

[00:02:50] And an upstroke two-stroke develops power on every downstroke and it pulls the intake charge in on every upstroke and does the compression as well so it actually it kind of combines up what has to combine operations on each stroke since there's only two strokes to accomplish them and there's four operations so on a two-stroke usually when the piston is moving down after having detonated the fuel air charge at the top developing power on its way down at a certain point

[00:03:26] The piston will uncover a transfer port that is cast into the crank case of the engine and it'll pass over this port and open it up which will thereby in this particular case on the downstroke will open up the intake port almost kind of like a valve but that we don't have any moving valves in a two-stroke so once it opens up that port it opens up the channel all of these crankshafts on a front intake anyway on a rotary intake type two stroke opens up that channel between the

[00:04:01] Carburetor and the top of the combustion chamber so the crankshaft is hollow and then it provides a port via that cast-in opening in the crank case and then it provides a path for that fuel and air to travel travel from the carburetor up to the intake or up to the combustion chamber so on its way down it opens up the port a little bit of negative pressure inside there as those exhaust gases are rapidly cooling after having been ignited by the glow plug at the top of the stroke that negative

[00:04:37] Pressure pulls in that fuel air charge runs it up through those channels that have now been opened up by the piston and allows that stuff to get to the top of the piston to get it ready for the next phase so the crankshaft goes through a bottom dead center now we're going on our way back up the piston closes off that port seals off the combustion chamber and on its way up it compresses all of that stuff and then once it gets close or very very close to the top of that the heat of that compression and the glowing element in the glow plug and the and the high pressure that's in there

[00:05:13] Is enough to ignite that mixture and we start the process all over again the piston heads back down passes the exhaust port the gases go out and then the piston goes and opens up that intake port again and the whole process is repeated all in one revolution of the crankshaft so that's why you can get so

[00:05:35] Much power out of a two-stroke then because each one of the the revolutions isn't actually a power

[00:05:40] Stroke exactly and that's why they generally speaking they turn more rpm because they're depending on that on the velocity and the and the variable pressures or the the varying pressures between intake and exhaust to pull that well to both pull the fuel air charge into the cylinder and then again to push the expense stuff out it has to develop a lot of pressure and momentum and you do that through rpm generally speaking that's why two strokes turn such a high

[00:06:10] Amount if you will or much higher rpm than the similar size four stroke because the four stroke doesn't really rely on that velocity so much as as the two stroke does to to move that air fuel charge i'm hope i'm doing a good job explaining that it makes sense in my head yes so far i'm understanding

[00:06:30] That's that's good okay so a four stroke then it does have the valves and those are run off of the camshaft so how how does that whole situation work then what's the what's the four strokes as

[00:06:43] Opposed to the two on that one yeah so a four stroke engine accomplishes all four of those operations suck squeeze bang blow in two complete revolutions of the crankshaft so basically there's one stroke for each revolution a down stroke and an up stroke so if we're doing two revolutions that's four strokes so that's where we get the term four stroke or four cycle some you want to call it something else you can call it a cycle and that's the same principle that pretty much all 99.999 percent of automotive application automotive internal combustion engines

[00:07:22] That's how they operate on the four cycle four stroke principle and basically what we've got is instead of using cast in transfer ports in the crankcase we're actually going to control the fuel air charge and and the other operations by opening and closing valves with using

[00:07:42] The camshaft like you mentioned so the four stroke is a lot more difficult to maintain i shouldn't say a lot more difficult but there's more to it there's more moving parts

[00:07:53] Right yeah it's not difficult it's just more more to think about and more to maintain

[00:07:59] Yeah like a four stroke engine is more in depth i guess when it comes to owning it based on what you have to do with it and and how you keep it in adjustment

[00:08:08] Right right and it's and it's really important because whereas on a two stroke there's really not once once you set it and forget it right once you get everything working correctly on a two stroke which is basically just adjusting the carburetor which we'll talk about later you don't you don't really have to adjust anything over time with a four stroke as with as with early car engines they they did require frequent adjustment and our modern even our modern airplane two four strokes that we're using require maintenance

[00:08:43] We have to adjust the valves occasionally to adjust for wear and clean bearings and and things like that make sure the valves are not carboned up so they're getting a good seal on the on the valve seats and things like that so yeah there's definitely more maintenance to them but the advantage of a four stroke number one in my book is the sound i mean they sound they sound really really good i think they sound a lot like a real like a full-size engine and another yeah just a little smaller right yeah exactly yeah yeah a lot smaller in some cases but the

[00:09:19] The other advantage is that they because they turn at a lower rpm they're a little bit more efficient so they're they're a little bit better with fuel so that you get a little bit more flight time out of the similar sized tank compared to a similar size two stroke but they turn they can they develop a lot more torque so you can turn a bigger propeller and that that's advantageous when you're flying things like airplanes that had big propellers like warbirds for example so that's that's that's some of the

[00:09:54] Advantages of the four strokes and i'm i'm a huge fan of them i i have several and i and i love them

[00:10:00] The four strokes then are still when the when the cylinders let's let's start at top dead center okay so when that comes down the first stroke is going to be the the valve is going to open and let the there the intake valve is going to open and let the fuel air mixture in exactly and then when that hits bottom that first stroke that's going to close and make sure i'm right on all these yep and then good that next step up right so that next step up everything is all sealed tight

[00:10:30] And that piston goes to top dead center and when it hits the thing okay so that's the what was it what was your thing again i'm not sure there's that for a while suck squeeze bang squeeze so that's the squeeze portion exactly and then when you hit the top that's going to be your power stroke so that's going to be your bang and then as that's going down that's where you're making all your power right and then on that final stroke up that is when the exhaust valve is going to open and that's going to let all that gas out exactly yep so that's exactly right so you're only getting one power stroke

[00:11:05] Out of out of two rp or two revolutions as opposed to on every one that you do in a in a two stroke yep exactly right so okay well i understand that a little bit then yeah so yeah there's there's

[00:11:19] Advantages and disadvantages to both everybody everybody has their favorite my favorite are four strokes i just really like them i'm as you may have been able to tell i'm very hands-on i like to tinker and and four strokes suit me because they require tinkering yeah whereas i'm kind of the

[00:11:40] Opposite i i like things just to work when i want it and i don't want to have to mess with it too much

[00:11:43] When i'm not using it yeah and i can i can certainly see the appeal of that too

[00:11:48] Yeah and it depends i think on the airplane if you have one that you're just going to go out with every day to to fly for 15 or 20 minutes electric is so nice and easy but you're right going out to the field and actually flying like an airplane that sounds like an airplane right yeah i mean there's a lot to be said for that sound i really do like that a lot more and the

[00:12:11] Smell too i really like the smell of that fuel and they look cool i think the four strokes look cool especially the early ones when they when the valves were or the i'm sorry the rocker arms were exposed way back when they just look look so cool when they're running seeing the the rocker arms move up and down what's happening inside it's just it's just very i don't know i don't

[00:12:32] Want to say soothing but i just like it yeah well and i like the looks like the the sato golden knight too the the black with the gold really looks good too on the the valve covers i i like those quite a

[00:12:43] Bit yeah yeah it's a shame to stick those in a cowl sometimes but gotta do what you gotta do

[00:12:49] That is true but if you have or if you don't have the room under the cowl you cut nice little holes and you can still see that sticking out just a little bit so that way it's under it

[00:12:57] So yeah we should probably talk a little bit so that's the difference between two stroke and four stroke probably should say a few things about setup right so obviously these these engines run off of a gas and that gas has to be contained in something so we put it in a fuel tank and there's a few things you should know about fuel tanks so generally speaking they should be installed in your airplane such that the center line of the tank lines up as close

[00:13:28] As you can to the max extent possible lines up with the center line of the carburetor and the reason for that is we don't we don't want to siphon fuel into the carburetor if the fuel tank happens to be sitting above it and we also don't want to starve the engine of fuel because the engine has to work so hard to pull fuel out of a tank that's too low so generally speaking we try to install the tanks so that the center line lines up with the center line of the carburetor or the venturi i should say of the carburetor and then there's different types of tank setups we've got two line

[00:14:02] Tank setups and three line setups and some i think there's probably a tank out there that you probably use one line it's a we would call that a bladder it's

[00:14:13] As a fuel is drawn out of it it shrinks the bladder kind of like a balloon and then when you put fuel back in it it blows back up i've not seen one of those before i it's been a long time i i don't i don't think they're made anymore but i i have a long time ago i i've seen them i can see how that

[00:14:29] Would be a pain a pain yes but the advantage of that was you never had air in the tank so no matter what position your airplane was in it was always getting fuel which is going to get to what i'm talking about a two line and three line setup so most most standard two stroke and four stroke model engines will use a two line setup so basically you've got you've got your tank and then coming out of your tank you have two lines two fuel lines so one would be the pickup and then you

[00:15:00] Have a vent so that we're not compressing the tank as we're pulling fuel out of it because creating vacuum so we'll have a vent and more often than not we'll have that vent line connected to our muffler and the reason for that is it will pull a little bit of positive pressure out of the exhaust not not so much pull but a little bit of the positive pressure out of the exhaust will kind of make it to the tank to help pressurize the fuel to help with fuel draw

[00:15:28] So that's a two line setup a three line setup is exactly the same but it adds a third line that you can route somewhere convenient outside the airplane to use as a fill so for instance on a warbird if we're using a fully calden engine it might be kind of hard to get to those lines to unplug them so that we could fill the tank unless you're using a fuel dot which i'll talk about in a minute so in in times like that where it's hard to get to those lines we'll run a third line out somewhere outside the cowl with a cap on it and we'll uncap it to fill the fuel tank and

[00:16:05] Then we'll cap it back off when we're done filling so with that with a setup like that then where you can't get to get to your your carburetor your exhaust port or i'm sorry or your muffler for for checking how do when the tank is full because usually when you fill up a nitro engine you you take both of those off and you fill you fill until it starts to come out of one of the other the lines right so how do when it's full when we're filling a tank you

[00:16:33] Know we have the vent line usually routed to the top of the tank where the the last remaining air would be as we're filling the tank right so when the tank gets full fuel flows into the vent line and then like you said we'll have that unplugged off the muffler so we can watch it as we're filling it on a fully cowled in engine it's a little bit more difficult because obviously we if it's really fully cowled in we can't reach that line to pull it off the muffler so and and as crude as this sounds in in case in installations like that i'm usually looking

[00:17:08] For fuel dripping out of the out of the exhaust pipe be it a tune pipe or a muffler or what have you or i'm listening for fuel to be squirting into the muffler i know that's crude and there's probably better ways to do it but but not without going to a multiple three or four line even set up on the tank most tanks are set up to do three line you may have to make a small modification to the stopper the stopper on the tank is usually molded with three holes but one of

[00:17:42] Them being closed off because most folks are going to opt for a two line setup and you don't need that third hole but i've never seen a four line setup so on a fully cowled in engine with a two line setup and a fuel dot which i was going to talk about yeah you're just pretty much listening or watching for raw fuel coming out of the exhaust as your indication or if you can see the tank you can see the tank and on my on my p40 the tank happens to be right underneath the

[00:18:13] Top hatch that i use to actually turn the airplane on so i can actually watch the tank as i'm filling it and in that case you have a nice fully cowled in engine i don't have to listen for extra fuel running out of the exhaust or wasting fuel or anything like that so a fuel dot

[00:18:32] You can use that with any any type of system usually done with a with a well okay so there's i shouldn't just say fuel dot a fuel dot is a basically a an extra line on a three line setup that you run through a nice little fitting through the side of the fuselage or the bottom or whatever with a cap on it same same idea as a three line setup that i mentioned earlier that you run an extra line out convenient that you use for filling a filling valve is something entirely different

[00:19:04] A filling valve i think dubro still makes some sullivan used to make some i believe

[00:19:11] There were other ernst i don't know if they're in business anymore but they used to make them and what that is it's a it's a valve actually that plugs in line with your fuel feed line to the carburetor and you have this special little fitting it's a it's a fitting that bolts onto the side of the airframe and then you have this corresponding fitting that you use with your with your fuel pump and it plugs into this valve and when you plug it in it closes off the feed to the carburetor and opens the feed back to the tank so fuel flows in through the valve straight to the tank it's closed

[00:19:44] Off from the carburetor so you don't flood the carburetor and then the same rules apply just watch for raw fuel or watch the tank whatever when it's full you unplug that and the valve reopens and remakes the connection to the carburetor and off you go so that's the difference between a fuel dot and a

[00:20:00] Fuel filling valve so the way i kind of see that then is like a like an electrical switch like a normally open or normally closed switch so you have your power that's coming in one side so that's going to be the part going to the carburetor and then based on whether or not you have your your fuel plug in there you're either going to have the connection going between the carburetor and the gas tank or the way i think about it too is that's like how your electricity would flow so that's going to be your flow when you put the when you put your fuel valve in there that stops all the

[00:20:35] Flow going to the carburetor and then that takes the flow to your valve which is where you're going to be filling it up so it's it can't go both ways it's a switch so it's either going to go one way or the other so okay i understand that now yep okay yep so there you go i hope i haven't

[00:20:51] Confused everybody on fuel tanks but it's it's a lot simpler i think than i explained it but basically on most sport airplanes we're going to go with a two-line setup and we'll go with a three-line setup usually for airplanes that are a little bit more scale or if we're trying to maybe hide the fact that this is a model engine on a on an all warbird or whatever

[00:21:11] So then that's the fuel dot what you were talking about with the right with the fitting okay yeah yeah okay i get it so what some of the other things then with tanks so when you install them into the airplane you said in line with with the carburetor is there anything else you need to kind of worry about when you're putting them in there and like how big of a tank do you

[00:21:33] Want to go with so yeah on the size of the tank i generally speaking i try to fit as big a tank as i can in the available opening within reason most most fuel tanks are going to be mounted ahead of the cg usually so you want to be mindful of of that a full tank is gonna maybe make it a little nose heavy as opposed to an empty tank so within reason i try to go as big as i can

[00:22:03] You want a little nose heavy as opposed to being tail heavy but when you go to like after you assemble an airplane you go to do the the center gravity you do the cg balance on it would you do that full or empty on a tank empty that okay so that makes sense then when it's empty you you check your center gravity that way when you fill it it's going to make it more nose heavy yeah assuming right assuming that the tank is ahead of the cg yes which most of them should be

[00:22:31] Right yeah i mean like most of our sport planes now some of these larger airplanes like like my big yak and i'm pretty sure like your really huge yak the fuel tanks are mounted pretty close to the

[00:22:42] Cg because their tanks are so large it is but it's it's a little four of the the cg so it's it's just a little bit forward part of that or of the the wing bar okay yeah so yeah weight and

[00:22:57] Balance check them empty a tank empty when you're doing your your cg but but anyway yeah so as big as possible within reason a 40 to 60 size a 0.4 to a 0.6 cubic inch engine sized airframe 12 ounces usually a 12 ounce tank is going to get you depending on your your flying style it's 15 minutes easy so there's there's usually i'm i'm done after about 10 to 12 minutes to be honest either i get yeah your neck can start to get your

[00:23:32] Neck can start to hurt after a while right so within reason as big as you can and as far as other yeah like so on the installation i think you this is the road you were kind of leading me down you want to try to isolate that tank as much as you can from vibration and we do that by either wrapping the tank in foam rubber or i've seen some airplanes actually will have like a hole in the the shelf that it's sitting on and it'll suspend the tank via rubber bands or whatever in that hole anything you can do to prevent vibration from getting to the tank you should do because

[00:24:07] The fuel that we use if when it's subjected to the the vibration especially the two strokes can can do with like a unbalanced propeller or whatever which we'll get to the the fuel will actually kind of foam up and then foam it doesn't burn quite as nice as our as our fuel does so burns much better in liquid state than a foam so we want to try to avoid that so we try to wrap them in foam or otherwise somehow try to isolate them from vibration

[00:24:42] So if you if you do get like a foaming issue then what does that make it run a little bit more lean

[00:24:47] Then because you're pulling air in or how does that yeah well so it usually shows up as a lean condition but mostly it's just it shows up as kind of an erratic hard to tune like at idle it may run just fine but then when you really start to ramp it up it it maybe it's lean one second and then okay i've i've added some fuel now it's really too rich it's just very hard to tune because the fuel supply is inconsistent okay i get that then yeah you want to talk about glow plugs

[00:25:17] Sure yeah yeah i can so talk about plugs i okay so there's different plugs i've seen there's some hot plugs and there's some cold plugs what's the difference between those oh man there's there's hot

[00:25:32] Plugs there's cold plugs there's plugs in between so basically when when we're talking about the the the heat range of the plug a hot plug is going to hold on to more heat during operation than a cold plug and it all has to do with the thickness of the the element and the length of the element and all this other stuff but basically plugs you can now of course every engine is going to come with from the factory with a recommendation right and we should try to stick to those whenever possible

[00:26:07] So like for instance most os two strokes they recommend an os number eight which i think is a medium i think plug heat range but you can kind of use plugs to fine tune the ignition timing if you will let's say with with all things being equal and your your engine is running great on a medium like let's say an os number eight plug if you go and you swap that

[00:26:38] Plug to say a hot plug it's going to create it's going to set off if you will that mixture that that fuel air charge on the top of the cylinder a little bit earlier i mean we're talking like fractions of a fraction of a fraction of a millisecond but i mean it it can fine tune so

[00:27:00] If say maybe you're gonna race let's say you're inducing pylon racing and you want to you've got a tune pipe and you got all this other stuff to to really kind of extract the most power out of this two stroke you might be able to get a even a little bit more power by increasing or advancing the timing by adding a hotter plug than what you were using to set off that mixture a little bit

[00:27:27] Earlier does that make sense so then what would the like the negative side effects be of of running

[00:27:34] When it's hotter the biggest disadvantage and this this applies to really all internal combustion engines an ignition that is too far advanced or an explosion that is happening too early

[00:27:47] Subjects the engine to tremendous pressures in the on the connecting rod that's the piece that connects the crankshaft to the piston and explosion that's happening before top dead center or i should say too much before top dead center you're now then trying to force that piston down because of the explosion before it's past that top dead center and it creates a tremendous amount of stress it's called detonation and it can be it can be devastating to an engine creates and if

[00:28:22] Even even mild forms of it if left if left to go on can really quickly wear out an otherwise good condition engine so that's that's the big disadvantage and sometimes the disadvantage is you just you just lose power because you have passed that point of peak efficiency so you don't want to go with hotter all the time right and always i mean always always always especially with new engines follow the manufacturer's instructions if os says to use an os number eight

[00:28:55] Plug then use an os number eight plug if if your brand new evolution says to use a

[00:29:03] Mccoy whatever then use whatever they tell you to do and you really shouldn't need really ever to tinker with plugs but if like me if you're if you're in and out of the market and you happen to pick up a used engine and there's it's an older one maybe you can't find any support online or any information on it it's usually pretty safe to start with a medium plug and then maybe

[00:29:27] Fine-tune from there if you need to like a normal person then just flying every day we'll never have to worry about the temperature on their plugs it shouldn't no no i mean so there there's is there any difference between what or what plug you use based on like temperature outside or does that

[00:29:43] Have nothing to do with that that that really it really doesn't i'm not by any means an expert like i'm not i'll throw out a name clarence lee he's a like a legend in model engine performance and and tuning and all that i have nowhere near that that sort of level but i can say that generally speaking most sunday flyers like myself once you use once you find a plug that works you'll you'll really never really need to to try anything else

[00:30:14] There's really just no need now after years and years and years of experience

[00:30:19] You'll develop kind of a sense if you will and you can just like it like a a race car engine tuner you can actually read a a model engine plug takes lots and lots and lots of experience to be able to to do that but the really good ones can do that so how do you i mean like how do you read what are you looking for well basically you're looking for the for the the condition of the element when you when you pull a glow plug out of the out of an engine you look down in it and you can see this little wire that's coiled inside

[00:30:54] There and that's called the element and just like just like full-size cars if it's if it's if it's dark and kind of sooty well the you're probably running a little rich which is okay a rich engine is going to last a lot longer than a lean engine right

[00:31:13] Especially with these two strokes and four stroke nitro engines that rely on that for cooling

[00:31:19] Exactly yep so you can you can you can determine quite a bit about the health of the engine but that it also goes without saying that you have to sort of start with a good plug to begin with if you if you're trying to read a plug that's been in your engine for three or four seasons and you're probably not going to be able to learn much from us you have to start with a new plug just just like you would with a with a with an engine mechanic in our cars they'll put a fresh set of plugs in there and they'll go run it

[00:31:50] And then they'll pull them and look at them and read them and we can sort of do the same thing like i said a dark sooty coil indicates maybe some rich running one that looks kind of white and ashy that one might be a little on the lean side so over years you can develop kind of an eye for that about how long should you get out of a glow plug that's a really good question i think it just depends it depends on how how hard you are on the engine

[00:32:22] Like do you fly at wide open throttle all the time or are you like me are you kind of lazy with the throttle you just like to putt around i think i think a lot of things go into how long these plugs will last generally speaking they'll last a lot longer in a rich condition than they will in a lean condition i think that's kind of the the case for all glow and spark plugs but but i mean i've got i mean i've got i'm looking at my contender here that super tiger's had that plug in it since i can remember and i've had that airplane i've had that engine on that airplane

[00:32:57] For at least gosh six eight years so i think it just depends so if it's taken care of and it's a well-tuned engine it's not something you have to worry about replacing like every season or twice

[00:33:11] A season or anything along those lines no no especially if you store your engines correctly

[00:33:16] Which we'll get to in a little bit so another thing on on glow plugs so okay so i've seen some and i think it goes back to my my traxis days if i remember right there are some that have a bar over almost like it's shielding the plug itself what what was that for yeah so that's called an

[00:33:37] Idle bar the purpose of it is to basically shield that little coil element from the raw incoming fuel which would otherwise extinguish it so kind of like if you got a an old coil burner electric range right you got that big coil up there and you got a red hot throw water on it and what happens it gets dim more the water hits it right well a glow plug that's dim is not going to do us very much good lighting off that mixture so an idle bar will help to protect that that coil from

[00:34:14] That cold incoming fuel and generally speaking and i hate to generalize but most engines don't need

[00:34:21] Those in fact i don't think i have any engines in here with a with an idle bar plug in it but sometimes

[00:34:28] An engine that's finicky maybe it doesn't like to idle but it runs perfect in every other aspect runs it transitions good it runs good at part throttle runs good at wide open it just doesn't idle well i can't get the idle down and it always wants to die at idle sometimes an idle bar plug will will help that you have to be careful though because an idle bar plug effectively makes that a longer plug so you have to make sure that you have proper piston to combustion chamber clearance you don't want to be smacking that bar with the top of your piston that would not end oh yeah that would

[00:35:01] That would break it pretty quick wouldn't it usually what happens is it breaks off the bar and then the bars in there floating around the the inside of the engine doing all kinds of

[00:35:11] Damage that won't last long no no it does wonders for your sleeve so so did the idle bars did the there or do the idle bars do anything like if your engine is inverted is that something that would be helpful or because i i guess with gravity you're going to have the fuel flowing down yeah it could

[00:35:29] It could help but but generally like i said an engine that is is that is in good tune and is in good condition generally speaking will not need an idle bar plug an inverted engine included like i have an inverted engine on my well it's sideways mounted but kind of the same idea on my p40 and i i don't ever that thing idles great so yes and no but try to get try to get your engine running properly with the plug that the manufacturer recommends and how do when it's time to change a gold plug so yeah

[00:36:04] The telltale sign is a hard start you've developed your starting procedure and it works like a charm every time it starts on the first flip or it starts within the first couple seconds of being on the electric starter or whatever and when you notice a change it's hard to start or it won't start first thing to look at is the glow plug and there's there's ways you can tell a plug is bad too you can test them so what's a what's an easy way to test the plug then so basically what i do is i i pull it out of the engine and then i hook it up to my glow igniter well just stick it

[00:36:36] On there and if it glows it needs to glow all the way down that little coil needs to glow all the way from the top to the bottom if it doesn't it has a couple of coils maybe at the at the base that aren't lit like the rest of them it's probably time for a new plug even if you have

[00:36:53] One that's lasted for six or seven years do you carry extras with you or do you have i do i mean

[00:36:59] Do you have a supply of them i do i keep i keep quite a few in my field box i always seem to be either loaning one out or i've i don't know ran an engine too lean or what have you i i do try to keep something because i hate to get to the field and then not be able to fly simply because

[00:37:17] I don't have a fresh plug that's frustrating it always seems like you forget something or do something and have to come all the way back home to get something and it's yeah it gets frustrating

[00:37:25] Yes so i i understand that well one one other thing i forgot to mention about reading the plug you can also read a plug to see if your engine is is detonating it's in that condition where we're trying to light the fuel too early and and usually the signs of detonation will first appear on the plug especially if it's mild detonation and what you'll look what you'll see is you'll see the coil won't have a nice uniform coiled shape it'll be misshapen somehow or maybe pushed off to the side

[00:37:56] A little bit not enough to short it out but enough to to not look nice and uniform i forgot

[00:38:02] To mention that but i actually know what you're talking about i've seen those before yeah so now

[00:38:06] I know what causes that's that's good to know yep i'm guilty i've i've i've pushed them a little too

[00:38:11] Far on more than one occasion so when you're okay so when you're flying obviously i think we'll probably talk later about how to start these things but when you're flying you're not running any power to this glow plug so does it still does something it won't run without a glow plug correct you mean the engine won't run without right yeah so the engine won't run without a glow plug right what so what what does that do like how does that work when it's in the engine

[00:38:38] So there's a there's a chemical reaction that's going on well actually it's a chemical reaction that is sort of propagated by heat and pressure so that element i think it's i think it's made of rhodium i think or or some other form of that type of metal and so when we when we first start our engine we have to we have to get the process going so we we clip on a volt and a half 1.2 volts whatever whatever you're using and it lights that coil it basically creates a short

[00:39:14] Like in the plug and current rose flows through that coil kind of like a light bulb if you will not a short i guess i shouldn't say a short but anyway we start the process off with the battery and then once the engine is running the heat and pressure of compression happening every stroke or every other stroke on a on a four stroke in addition to the methanol that is in the fuel creates a chemical reaction to keep that element glowing so that the process of ignition can happen

[00:39:46] Every every time it needs to happen so that's what's going on and that's why we can pull the the the one and a half volts off the plug after it started because that process is going and that the chemical reaction and the heat and pressure of combustion is keeping that whole

[00:40:03] Process alive so that kind of works like my i built a hot wire cutter for some foam and i think that's nichrome wire like or nickel chromium or something like that wire okay and that kind of does the same thing then i guess is what you're talking about when you heat that up because you apply voltage to it and depending on how long that piece of wire is that i'm using it it's a

[00:40:25] Different voltage yeah the big difference between your your foam cutting wire and a two-stroke or a four-stroke model engine is when you pull the power off of your wire it it goes dim and gets cool whereas we pull the power off of ours when the engine is running it continues to glow right yeah

[00:40:42] But that's only because it's under such immense pressure and has the the fuel to kind of keep it going too then right yep but okay well then i understand kind of how that works and then

[00:40:52] When you're testing glow plugs yeah you want to be careful because they do get hot so if you're holding it in your hand like i do don't check it quickly and then pull it off the heat because it will get hot and it'll burn your fingers you ask me how i know that yeah how do that i've been there done that like it's a it's funny i've been such a i've been a hobbyist for so long like the tips of almost all of my fingers have no feeling in them because they've been either burnt or cut or sanded or whatever so anyway but you're not you're not doing a lot to tell people this is a

[00:41:28] Good hobby to be in but i i mean it's there's something to it right because i keep coming back

[00:41:35] Oh apparently i guess a glutton for punishment or something yeah yeah so would you you want to

[00:41:43] Talk about how to start one yeah how do you how do you start one well what's your procedure

[00:41:48] Do you want to talk about your procedure well i can kind of go over what i do i don't i don't have a lot of experience with nitros i've only been flying for for a few years compared to you yeah you don't you don't have any trouble getting your airplanes going no but i don't know as much about everything that's going on with them if that makes sense i feel like i'm dominating the conversation i'm trying to give you a chance here oh no that's okay i mean i i don't mind okay but i i understand how like the basics of them but when it gets more in depth i've never really gone into it and learned

[00:42:19] About them they're they're actually pretty cool little engines i mean there's there's a lot that goes into them and they they're they're kind of amazing little pieces of technology when when you kind of look into them a little bit more yeah and what's really amazing is how old this

[00:42:35] Technology really is i mean these oh is it i mean two-stroke model airplane engines go back to the 40s 30s even i think it's it's really quite quite remarkable sorry that is no that's okay that

[00:42:50] Is a long time ago though i remember when i was a kid i had one of the the cocks 049 little control line things i never got it started though because i never had anybody mentor me like like you had your neighbor do right i just i i know my parents bought it for me and i just i i i'm thinking and this is way off topic i'm sorry but on those do you remember was there any kind of like a spring starter or something on it to where you'd like wind it a little bit and then let go or was it just a no they had yep some of them had spring starters okay because the one i had

[00:43:26] Did and i remember cutting my hands like several times yeah before i started using a stick to do it so oh yeah yeah and like i said unfortunately i didn't have like my dad and stuff wasn't very mechanical okay he was he was very mental not oh that didn't sound right he was he was academic he was academic he wasn't hands-on with a bunch of things like i am i know what you mean okay well i want to make sure everybody knows what i mean when i said that because

[00:44:00] That that sounds ron's dad is not mental he's just very academic academic that's a better word for it but anyway so when i was young he wasn't into that he didn't know how any of that stuff works so that's i kind of got i got that i think as a birthday present or something and yeah like i said never got it to run and after listening to all this i i realized i never had a glow plug igniter so i never had a chance to begin with so that's kind of funny that is kind of funny

[00:44:28] So you were trying to start it trying to start it trying to start it and never had any heat to

[00:44:32] The plug never had nope never had any poor kid i know right it's amazing i stayed with airplanes

[00:44:40] After i really got back into them later especially knowing how you are you like you just like stuff

[00:44:45] To work that's funny i i do i i get upset when things don't work the way they're supposed to

[00:44:50] Yeah but well i could see that see i mean that would turn a lot of people off that that

[00:44:56] Sort of first experience yeah but see i think after that i ended up with do you remember the the little battery operator it looked like a flashlight i think it took like three or four d-cell batteries yeah and what i'm talking about yet i had a little button on it yeah

[00:45:12] And it had a wire and it just flew around in circles above your head right so the the motor was actually

[00:45:17] Inside this little thing that looked like a battery you press the button and then there was a wire that went up to this airplane it was just a little plastic plastic and cardboard airplane that had a propeller on the front of it and when you press it that motor spun all the way through that wire and went up to the propeller oh my gosh i got i spent hours just like going in circles with that thing i was getting really good at like taking off landing and all that stuff with it that i really really enjoyed and i remember that was i think that was probably right before the bigger control line

[00:45:48] Airplane i think that's why they got that one for me the cox one oh i got okay because they saw that i was into that one and i i don't think they knew what they bought when they bought it

[00:45:58] They just saw i'm seeing a bigger i'm seeing a trend i'm seeing a trend here so your very very first airplane was electric and your second airplane that you had terrible luck with was the nitro

[00:46:11] So that's why you have an affinity for electric it could be it comes full circle i never ever thought of that but yeah that's amazing and my first actual radio controlled airplane was an electric one too there you go see oh that's funny making connections oh we got off on a tangent on

[00:46:29] That one i'm sorry that's okay yeah i'm sure somebody will find that amusing i found it amusing so

[00:46:35] There so back to starting okay when i start it's it's very simple we talked about filling the tank already so i make sure the tank is full right really all i do is i well first off you got to make sure that your glow plug igniter is charged yes the ones i have are they run off of rechargeable batteries so you just plug them into your into your into your charger and make sure they're charged the night before yep you can get them with just regular like c or d cell batteries

[00:47:07] I actually i think those work pretty well too because you don't have to worry about keeping something charged yeah i actually prefer those yeah i ought to look into getting a couple of them

[00:47:17] Just to have on hand and can i can i just tell you the reason i prefer those sure because of the voltage a regular alkaline battery puts out one one and a half volts yeah and rechargeable puts out a 1.2 something like that yep that's that's kind

[00:47:37] Of what we talked about last time and then that's the other thing too the nimh batteries have a lot of drain in that first 24 hours so exactly it's it's good to have something you don't have to worry about charging so yeah i probably ought to look into getting a couple of those well and the

[00:47:52] Extra voltage is good for lighting the plug too yeah i mean the plugs are rated for 1.5 volts so why not why not use 1.5 volts that's the way i look at it no you're right anyway sorry i'm not

[00:48:06] Going to argue no argument here so let's see the next thing i do after i have the glow plug on i get out my electric starter and put it on the front and spin it until it starts okay and then i let it run a couple seconds take the glow plug off and put it on the ground and hold it down run it up to full throttle and then do my pre-flight and go that's yeah i know you do a little bit

[00:48:30] Differently so well that's that's almost exactly how i would have would have described it there's just a couple of things i would have i'll do first so fill the tank just like you said cap off the vent line or put it back on the muscle or whatever and then i try to make sure i get a good prime so i don't want any air bubbles in the fuel system if i can avoid it so i'll prime the engine and which serves two functions actually it gets it gets fuel into the engine so that it'll

[00:49:01] Run and then it also pulls air bubbles out of the line so i do that before i even think about lighting the plug and then once i have it primed and i prime it to the point where it sounds it's hard to describe it sounds wet or squishy if you will and and my method for priming is a cup you can do it a couple different or i can do it a couple different ways depends on the installation that my preferred method is to without any glow heat on i'll run the throttle all the way up so

[00:49:34] The throttle barrel is all the way open and then i'll plug with my finger the exhaust so just put my finger over the exhaust outlet and then i'll flip it over a few times and usually within within three or four flips i've got fuel drawn up to the engine from the tank and fuel actually sitting either in the intake or in the in the cavity of the crankshaft or whatever i have some fuel in the engine within a few flips and then i'll take my finger off the muffler and i'll flip it a few

[00:50:05] More times vigorously with the throttle open and then i'll close the throttle to idle and then i'll do

[00:50:11] Then i'll carry on from where you said you started you do all your starting by hand though

[00:50:17] I do i i can't say all i mean i do have a couple of engines that are kind of stubborn and and probably due for a rebuild because of the low compression so they're a little bit harder to start and i will use on occasion an electric starter but i do i do prefer to hand start all my

[00:50:38] Engines to include my four strokes so what's the is that just a personal preference or is there anything that's actually like better for the engine to do it that way ask four different people that

[00:50:51] And you'll get four different opinions my opinion is i think hand starting is is probably easier on the engine i think you run less risk of damaging the engine if you should happen to say have a flooded engine and you're putting that electric starter on there and the the combustion chamber is full of gas that by the way it's hard to compress liquid right right so with that electric starter you could bend bend a connecting rod or you could do all kinds of damage if if you're

[00:51:22] Not careful i just don't want to take that risk right so yeah and so then like an inverted engine is that more difficult to start does that have a higher higher chance of flooding

[00:51:34] It can especially four strokes because of the intake and the way they're set up and the long exhaust track if it's inverted of course everything is going to run to the to the cylinder so when right if you have a large amount or a large volume of liquid in the intake and that intake valve opens it's going to go straight into the combustion chamber so yes potentially you you have a little bit more risk of flooding an inverted engine but if you're

[00:52:03] If your fuel tank and everything is set up correctly and you've and you've primed it you

[00:52:08] Know and not over primed it then usually you can mitigate that risk but yeah you you can it's possible to run into starting issues with inverted engines but if you're using your hand you'll know those problems before they before before you potentially bend the connecting rod by trying to

[00:52:26] Crank it over with an electric starter so you'll just you'll feel more resistance then or you won't be able to get past that compression because of the because of the extra fuel in there then if

[00:52:37] It's flooded yeah if it's if it's flooded you you it'll be very difficult to with your hand rotate it

[00:52:46] Through the the compression and over top dead center because you just can't compress a liquid you'll know by hand and so then if you're using the electric starter though there's nothing to let that it's it's getting to the point where you need to be careful and that's when you can actually do

[00:53:00] Damage then okay right like how many times have you have you been to the field and you've seen somebody using an electric starter and they put the starter up there and it fails to turn the engine over so what do they do they they pull the starter off harder exactly they'll they'll move the pull the propeller back away from the compression stroke and then they'll get like a running start at it right they'll fire up their starter and then jam it onto the spinner i mean you've

[00:53:23] Seen it right i have yeah i definitely have yep yeah don't be that guy yeah there's a reason it's

[00:53:31] Not starting that yeah i'm just teasing i mean people do what they have to do like i shouldn't

[00:53:36] Judge well no it's not judging it's you want them to to not damage their equipment right and if they don't know what's going on like i never would have thought anything about doing that it just seems like it makes sense if it if it's because your your starter doesn't have enough power to turn it over well then that's how you would do it i suppose but yeah if you don't realize there's an underlying issue that you need to deal with right as of why it's not starting or or why it's having problems then you don't know if you don't know you don't know i mean i don't know how else to put it other than that so right yep it's good to good to know what's

[00:54:10] What's going on so you can do things appropriately and not damage your your materials right and i mean you

[00:54:16] Know back when the hobby started we didn't we i shouldn't say we i wasn't i've been in a long time but it wasn't it hasn't been not that long but there were no such thing as electric starters so you had to develop a technique to start them by hand otherwise you weren't flying yeah so so i i prefer to do it by hand and i've got a little technique that works for me and i i have pretty good pretty good luck i think really quick though the other thing too

[00:54:43] Though is you can not really damage your your hub but you can really mar up like your spinner on your propeller too if you're using a starter like that so that's another good thing is it kind of keeps your plane looking prettier longer right without having all the the marks from that the starter on it so yeah but yeah if you want to get into your into your starting

[00:55:08] Thing that's fine yeah so i i prime the engine like i like i described there and then once i have it primed i'll close the throttle to idle and i'll give it a a couple more good flips through the compression to sort of distribute that fuel throughout the engine and then and then yeah i'll i'll put the i'll put the glow heat on and then what i like to do is i like to back the engine up against compression and then i just basically on on most not all but on most of my engines i'll grab the spinner and i won't even touch the propeller i'll just give the the spinner a

[00:55:43] Quick right hand flip up against compression and usually that's that's enough to get it going

[00:55:49] If that makes sense so you run it backwards are you trying to start it backwards yeah well i mean i'm

[00:55:57] Not trying to start it backwards but that's the motion right so like as you're looking as you're facing your engine as you're looking at it when it's running it's it's going counterclockwise right correct so when i'm starting my engine actually before i put the glow heat on after i've done my couple of vigorous flips i'll i'll turn the propeller clockwise until i reach compression right i won't force it i'll just kind of turn it until i until i bump it up against compression and then i'll put the glow heat on and then i'll just give it a little flick

[00:56:31] If you will up against that compression and usually that's eighty percent of the time maybe that'll work on the first try if i've primed it correctly a point of safety you should never fire up your airplane without assistance like somebody holding the airplane because if this thing fires off and you've got nobody to hold it i mean there you are exposed and here's this thing coming at you or moving away from you bad news so always always have a helper there to hold the

[00:56:59] Airplane when you can i'll just say it that way can those run backwards yeah they they do fire up and

[00:57:06] Run backwards sometimes and usually a quick little blip of the throttle and that's usually enough to either kill it or get it running the right direction and if if you have years and years and years of experience and what you're doing and you're comfortable around them sometimes you can correct them physically an engine that like a two-stroke that's running backwards at idle i'll kind of form my hand into a a fist with like a a little hole kind of like you're giving somebody the okay sign and then i'll just kind of cup the spinner with that real quick and usually

[00:57:41] That's enough to stop the engine more often than not it'll start running the correct direction oh without having to restart it even right usually huh yeah like i like i don't recommend

[00:57:52] Did anybody do that that's what i was just going to say that that sounds dangerous so if you don't know what you're doing or you're not sure just don't do it right yeah if if if you don't even feel comfortable starting it by hand use a chicken stick or use the the starter that's fine

[00:58:08] Yep yeah there's nothing wrong with doing that yep i usually always have a glove on i have a thick leather it's not really a welder's glove but it's a pretty thick leather i love how you said that by the way i usually always have it on well i mean sometimes i'm i forget i'm i'm getting older i tend to forget to bring things with me to the field yeah i sometimes always do that too i'm looking at it it's it's a big leather glove and i usually have that on when i'm firing up my

[00:58:40] Engines if you notice i've forgotten remember i mean i'm old and i've been doing this a long time i have lots of experience i'm not an expert okay but i i kind of know what i'm doing so i know the dangers and i know how to avoid them somebody who hasn't been doing it a long time may not be aware of the dangers so you shouldn't try stuff like that unless you're absolutely comfortable doing

[00:59:07] So yeah we're not condoning any of this right so just telling you what works for me do as he says

[00:59:14] Not as he does right yeah i'll give you give you my mom's advice yeah do as i say not as i do

[00:59:23] Yeah i think i was raised on that same motto i think a lot of us so anyway yeah that's how i that's how i start my engines so what's the difference between starting an engine just normally versus like when it's cold outside is there anything you have to look out for because we have winters yeah go out we we usually try and fly on january 1st yeah to which i usually bring in electric airplane because that's me but is there anything extra that you

[00:59:52] Have to do for for a nitro generally speaking they in in colder weather the the air is usually denser so they'll they'll require a little bit more fuel so you may have to richen up the needle valve but but basically the the biggest difference is they're a little bit or they can be a lot harder to start so they'll require either more flipping or in the winter time that's usually when i when i use an electric starter that's when it is it's just because

[01:00:25] I don't know the science behind it but the the cold and the dense air and they're just more difficult to start but but once they're warmed up they they run just like as if it was

[01:00:37] 90 degrees outside well that's interesting to get them yeah to get them started you

[01:00:41] Know sometimes a little extra prime helps without without flooding it but a little extra fuel in there to get the process started sometimes helps too so i wonder do they run a little bit better

[01:00:51] Than in the winter because of the denser air they make more power that's for sure make more power yeah oh yeah that's kind of common with all internal combustion engines right yep that you get more power with that the air that's condensed i guess it kind of works as a supercharger without

[01:01:05] Actually putting one on yeah yeah more or less i mean you've got a colder denser fuel or a fuel charge so yeah it develops you can get more in and more out so yeah you get a little bit more power yeah but they are a little bit more difficult to get going in the colder weather so you have to prepare for that frustration if you're going to fly in january yeah just be prepared

[01:01:32] So we are at about give or take about an hour mark right now okay we have a lot more to talk about true we now we still need to talk about tuning and all that stuff i think i would like to end this one for now and do like a part two oh yeah sounds good that way that way we're not not doing a two and a half hour episode or something like that so sure join us for part two and for now i'm gonna sign off then i am i'm ron and i'm tom until next time goodbye goodbye

[01:02:08] We hope you enjoyed this episode of the rc plane lab podcast for topic suggestions to ask questions or to give any feedback connect with us at rcplanelab.com or email us direct at either ron at rcplanelab.com or tom at rcplanelab.com you can also text us or leave us a voicemail at 818-351-9846 please subscribe rate and review us on your favorite podcast app until next time may your landings be gentle

[00:00:04] Welcome to rgplane lab a podcast for anyone interested in rc airplane we'll share tips and tricks on how to build models and talk about successful flights epic crashes and everything in between visit us at rgplanelab.com to sign up for our email list and to ask us questions you can also text us or leave us a voicemail at 818-351-9846 please help us out by rating and reviewing us in your favorite podcast app thanks for spending time with us today now here are your

[00:00:35] Hosts ron and tom hello everyone and welcome to the rc plane lab podcast this is ron i'm tom welcome to part two of our nitro engine series i guess you could call it in our first episode we kind of went over nitro engines glow engines if you will talked about how they work we talked about how to set one up we discussed glow plugs and and how to start them that one ran a little bit long so we decided to split this into two episodes and this in this episode we're

[00:01:07] Going to talk about how to tune them we'll talk about proper storage and care and then we'll kind of talk a little bit about fuel what we use to fuel them the difference in the nitro content and what's actually in the fuel that we use and then kind of whatever else we get to i don't know exactly where the conversation will go but we'll see so you never know you don't that's for sure so tuning let's talk about tuning a glow engine or nitro engine okay oh you want me to just get

[00:01:39] After it yeah just get after you let me know okay so yeah lots of lots of information it's a it's a skill that has developed over potentially years of of being in the hobby but eventually if you fly a model airplane that's powered by a glow fuel eventually you're going to have to tune it either it's going to not be tuned perfectly from the factory or as parts

[00:02:14] Wear in and it starts making more power you'll have to add more fuel so on so forth so eventually you're going to have to get comfortable if you will turning the needles on that carburetor

[00:02:27] Now one thing i will say though before we get in in too much to that so like i said before i started out like the first nitro things i ever had was nitro cars or nitro t max is really the the monster trucks before i really knew you but we were introduced way back when i remember you tuned my truck truck and i was so impressed with how you got i mean you had that thing running better than i ever could i i don't have the knack i guess for tuning those as as well as you do okay but one thing

[00:03:02] I have noticed though like with airplanes versus like the nitro cars and stuff airplanes are much more forgiving you don't have to be dead on like you do with cars to get that quick throttle response to go from idle to full throttle so it's i i can handle tuning an airplane

[00:03:22] To get to the point where i can fly it but you can really tune them and get them to where they're running just absolutely perfectly how they need to be running so that's why i want you to talk

[00:03:33] About this okay all right yeah i'm comfortable talking about that okay so first first we should we should start with let's say we're dealing with a new engine new engines today's engines they're they're built with these really really tight tolerances and they're designed to be broken in if you will a certain way and always follow the manufacturer's directions i'll always default to the manufacturer's instructions on on tuning and break in

[00:04:07] And and maintenance and all that and what plug to use which we already talked about but but i'm what i'm what i'm really talking about is is once we're past the break-in stage and an engine can be kind of hard to tune when it's breaking in because parts are parts are wearing in tolerances are changing it's going to change the demand for how much fuel it needs so an engine that is in the midst of break-in should be tuned how the manufacturer tells you to tune it but then

[00:04:38] Once the engine is broken in and is as part of your regular flying repertoire if you will that it will require occasional tuning and the way i do it as since i've been doing it for such a long time i've sort of developed an ear i can i can kind of hear if an engine is running correctly takes years of experience to sort of develop that some

[00:05:08] People develop it quicker than others some people have no desire they just want to go out there and fly and nothing wrong with that because there's usually always not always but there's usually somebody at the field who can help them out with tuning and at our field a lot

[00:05:25] Of times that's me and i'm fine with that you go up and down the line and adjust many airplanes when

[00:05:30] We're out there well i don't voluntarily do it i don't i don't touch someone's airplane unless they unless they ask for my help and i'm not that guy out there that says hey it's you're running too rich i'm not that guy if people come up to you and you you don't get a lot

[00:05:44] Of flying time in because when you go out to the field you do a lot of work yeah and and really you

[00:05:50] Know truth be told i i enjoy that because like i said i enjoy the tinkering yeah i think i think more so than the flying but at any rate so i've developed this this sort of ear that i can that i can i can tell when an engine is running lean or or rich just by the sound it's making and then i'll combine that experience with i'll look for the exhaust and lots of little clues that i can put together to determine what an engine

[00:06:24] Needs but for folks who are just sort of maybe maybe just getting into it or they don't they don't want to develop that intimate relationship with the needle valves tuning by rpm is is probably what i would recommend most folks do until they develop that that ear if you will so that requires a tachometer and and i'll describe the process so once we've got an engine running you let it let it warm up 10 15

[00:06:58] Seconds 20 seconds whatever let it get up to temperature let all those parts expand to the their normal operating range and then and then get to tuning so so what i what i do when i'm going to tune by rpm is i'll have my tachometer handy and i'll while i have somebody restraining the airplane i'll run run the throttle up to full throttle if if i just want to make a note of this if it doesn't if you can't get it to run at full throttle then you will sort of

[00:07:35] Have to rely a little bit on that that sort of technique that i that i use all the time which is sound and and looking at the exhaust so there's probably a reason you can't get it to run up to full throttle or you can't get it to run while the stick is at full throttle more often than not it's because it's too rich and you can tell it's too rich dead giveaway is lots and lots and lots of smoke and maybe even raw unburnt fuel coming out of the exhaust so that if if

[00:08:08] You have that issue going on and it's just blubbering blubbering blubbering and you get the stick to full throttle it just eventually dies i probably got to lean the needle a little bit at a time until you can at least get it to run with throttle set wide open and if it's too lean it does just the opposite it's a lack of smoke and very very high rpm and dies usually speeds up and then dies before you get to full throttle so that's one giveaway for a lean engine but

[00:08:40] Anyway you get it so that it can run at full throttle and then whip out your tachometer and take a reading and then gradually turn the needle the high speed needle that's usually the longer one more often than not on the left hand side of the engine most engines today have remote needles to get you away from the prop which is nice anyway get it up to full throttle without your tachometer and take a reading and then watch that rpm as you move the needle so let's let's say i always try

[00:09:14] To go richer first because you don't want to if you have a lean engine and you go leaner you're going to potentially damage the engine so as it's running at full throttle and you've got your tachometer taking a reading on the at the prop you rich in the needle and that's usually out okay on that main needle and then watch the rpm if the rpm climbs you were you were too lean so you want to keep moving that needle out until the rpm drops right and then once it does

[00:09:49] That then you can slowly begin dialing that needle in until the rpms no longer climb with each needle adjustment and once you've reached that point back the needle off a couple hundred rpm on your tach and you're ready to go that's that's in a nutshell how you tune by rpm questions no i i think i fell along pretty well so okay that's good it's just yeah it's just i mean like i said it's a and over

[00:10:19] Time if you do that enough you'll you'll sort of develop that you'll be able to tell you'll be able to hear when the rpm is climbing and then when it's not climbing anymore you you'll be

[00:10:31] Able to hear that yeah so the the handy little tachometers that we carry with us they actually work pretty well and you can you set them to how many blades the propeller is right because as that's working it it counts every time the blade goes by which obviously has to be divided by two for rpm if that's a two-bladed plot or prop or has to be divided by three or four depending on what kind of prop you have so yeah they're pretty smart little tools you have with you too that that really do a good job of letting what you're what you're running at right and i just

[00:11:05] Want to something you can kind of put in your toolkit if you will is a the sound that a that a rich or an extremely rich running two-stroke makes it sounds sort of like a four-stroke because in in essence what it's doing is it's firing on every other stroke kind of like a four-stroke wood so a two-stroke that's making that kind of four-strokey kind of a rough running sound is usually an indication of of an engine that's running rich and yeah so that's how that telemaster

[00:11:39] Was when i first got that started a couple weeks ago it was running very rich and it was doing that same thing i mean that that plane was jumping around quite a bit it it runs very rough

[00:11:52] Yeah with the gasoline engines it's it's harder still because they don't have all the oil that these that these glow fuel motors have in the fuel so they don't generate the smoke like these like these glow fuel engines do so it's harder to tell by by by sight if they're rich or lean yeah but with that

[00:12:12] One i could definitely tell though just by listening to it because it was it sounded very sad yeah and i was amazed like when it was when it was leaned out just a little bit i mean that it just got so smooth and i i mean i know it's gas versus electric or versus nitro but it's the same basic thing when it comes to that it is it absolutely is they they do kind of run the same way and so yeah if you hear that night it almost sounds like it's well like it's missing pretty much because it is and like i said just runs very rough it's not made to run firing every two revolutions so that's that's a

[00:12:49] A good indication that yeah you're you're very rich right yep a properly a good running

[00:12:56] Two-stroke will have a very smooth even sound to it without sounding like it's screaming if that

[00:13:06] Yeah makes sense no i get it yeah especially after starting that one up i know what you're talking about

[00:13:12] Yeah so there's so talking about the needles so there's a high-speed needle right that's the main one that's the one that controls the main mixture at the carburetor and so the

[00:13:24] The the high-speed needle will affect the low-speed needle sometimes but not always it depends oh really

[00:13:30] It depends on the yeah it depends on on the carburetor it depends on the manufacturer lots of lots of factors go into that but not always i mean i i can't even say generally speaking because there are engines out there that that the two circuits so the low-speed circuit and the high-speed circuit are two completely different circuits and one does not affect the

[00:13:53] Other okay i always thought that's why you did the high speed first so the high speed is like i said that

[00:13:59] Main one and on most engines it's like as if you're sitting in the cockpit it would be on the left hand side of the engine in most cases the other speed the other needle if it's a twin needle carburetor there there's there's twin needle carburetors and then there's not twin needle carburetors

[00:14:20] I know it gets really confusing but most engines today most modern engines that are on the market today they're going to have two needles so i'm going to go ahead and stick with that and then maybe i'll touch on the other ones briefly at the end but so there's the low speed needle on the right hand side usually of the engine and what this controls is like the name implies the low speed or the low speed circuit so idle mixture and usually this is where your transition sort of gets gets dialed in is with the low speed needle so once we've set the engine running running good

[00:14:58] With the high speed needle at wide open now it's time to set the idle mixture which which will also affect the transition and the way i do that is i've got the high speed needle tuned it's running great at wide open throttle it's making making good power it's running smooth it's getting plenty of fuel then i'll back it off to idle and the way i do it is before i get to that point like i've got it i've got it running at wide open and it's it's it's tuned to perfection what i'll

[00:15:31] Do if i can if i have access to it is i'll pinch the fuel supply line and it should pick up rpm and then if i keep holding on to it die and the time it takes to do that is what i'll sort of listen for if it does it really really really fast then i know it's probably a little on the lean side on the low speed needle if i do that and it takes a couple of seconds then i know i'm i'm really

[00:16:01] Close on the low speed and it takes time to sort of develop that but that's what i do first so by

[00:16:06] Pinching that though then you're putting it under a lean condition and that's why it speeds up

[00:16:11] Right right because it's running out of fuel and getting hot and it's advancing the timing and doing all these things because it's trying to run but it's not it speeds up and then it runs out of fuel and dies same same like if you've ever been like to a oh i don't know a a tractor pulling event or or like a drag race where they're where they're running these high nitro cars like when they when they shut off the fuel they always speed up before they before they die there's lots of reasons for that i'm not going to get into it but anyway that's

[00:16:41] What these will do also okay so so i i do that little test first and that'll give me an idea if i'm close on the low speed needle or not if it if it if i pinch the line and like immediately dies then i know i'm probably a little bit on the lean side once i got the high speed dialed in i do my little test i'll bring it back to idle and then i don't use attack anymore i i try not to get wrapped around the axle about trying to get the lowest rpm i can get at idle i used to be that guy i used to

[00:17:13] Want it to just sit there and just barely turn over but anymore i kind of favor an engine that will stay running in flight rather than one that dies unexpectedly so i'm okay with a slightly high idle as long as as long as it's high like low enough to not like keep flying the plane when i'm trying to land yeah as long as you can still land that you should be fine right so i'll back it down to what i feel is a comfortable idle and then i'll leave it there and i'll just let it idle and and i'll watch or i'll listen to what it does if it just happily keeps idling for 20 seconds 30

[00:17:50] Seconds or whatever then my work is is probably done but if it if it gradually kind of gradually slows down slows down and then starts running rough and sounds like that that rich condition then i'll start adjusting the needle and so there's two different types of low speed needles there's an air bleed and then there's a standard needle that's very similar to the high speed needle in is leaner and out is richer on an air bleed carburetor and you can tell it's an air bleed because

[00:18:26] A low speed needle will either cover or uncover an open orifice in the body of the carburetor and it'll be very easy to see and the instructions with your engine will actually tell you what type of carburetor it is so on an air bleed it that that it's backwards so in is richer and out is leaner because you're not adjusting the fuel you're adjusting the air does that make sense yeah

[00:18:56] You i get it so like on the the carburetors where you have the the set screw on the side of the the actual carburetor itself on the side of that what's the part of the twist what's that called the throttle barrel yeah the ones that are on the side yeah i think that's what we're talking about the the the part that the servo hooks up to where that goes back and forth okay so when it's on the side of that like the the the set screws on the side of that what kind is that

[00:19:23] Yeah so if the if the needle is is is like you said is in the middle of that throttle arm that's a standard type standard type needle okay and it works like normal out is richer and in is inner because what you're doing is it's a tapered seat that that needle is threading into and that seat is is connected to the fuel circuit not the air circuit so as you come out it opens up the seat allows more fuel you go in it closes off the seat and allows less fuel okay

[00:19:54] So if it's the the air bleed screw though is that a screw or is that a needle it's technically just a

[00:20:02] Screw that that either closes off or opens up like i said an orifice on the body of the carburetor and you can tell usually the dead giveaway is that the screw is not part of the throttle arm assembly or in line with the with the main needle it's it's usually like i said just a screw on the side of the carb body that either goes in to close off a hole or comes out to open up a hole okay i got

[00:20:29] You that so it's it's kind of easy to tell the difference on which kind you have when you look

[00:20:33] At it absolutely okay yep absolutely usually on a on a standard twin needle carburetor that operates that's not an air blade the two needles will be sort of if you will pointing at each other unless you have a remote needle then all bets are out the window okay so but are most of them

[00:20:53] Going to be the air bleed or do you think they're going to or does it even just depend completely on

[00:20:57] The motor it it depends on the engine like for a long time in fact i think os still makes their their higher end engines like i think they're either like ax is now i think is what they are those have the standard twin needle type carburetor and then their fp series which they're not fps anymore i think they're called la's i think it's a it's a a more inexpensive engine so there's not bearings on the crankshaft things like that usually those engines

[00:21:30] Were equipped with the with the air bleed style carbs because they they cost less to manufacture

[00:21:35] Okay is there a plus or minus to either one of them performance wise i think i think a standard

[00:21:43] Twin needle carburetor it's been my experience that you can that you can really really really fine tune that they're a little a lot finer in their adjustment but they are more complicated and they do take they do take more skill to get tuned really really to the nth degree whereas i think i think the appeal of the air bleed carburetors is they're simpler to set up and they're they're they're maybe not quite as sensitive to needle change especially on the low speed

[00:22:14] So they they may be they may offer a little bit easier adjustment okay but there's pros and cons to each one and i i don't really have a preference generally speaking though the air bleed carburetors are usually on engines that are that are a little bit more economical so they have plane bearings on the crankshafts and things like that so something to think about like the like the engine that's on the stick there and we're in the middle of recovering at your house that has a

[00:22:46] An os la on it which is one of those less expensive engines and i believe that one has an air bleed

[00:22:52] Carb on it but it runs good yeah it does you you've put a lot of time on that one yeah it's got it's got a few hours too bad it's blue it doesn't match your plan anymore i know i know i may have to strip

[00:23:05] It but so anyway so that's that's kind of the long and short of tuning but just to get back on the low speed needle you just you just basically you either rich in it or lean it depending on what type of needle you have based on what it does at idle so like i said i'll bring it back to idle and i'll let it idle for ever not forever but for a lengthy part of time and i'll just listen and watch what the engine does if it gradually slows down and kind of starts running rough and dies

[00:23:41] Then it's rich if i when i get to idle it speeds up and dies then it's too lean so then i only rich in it up or lean it out in the other condition until until i get it such that it will idle i would like to see an engine idle a whole tank of fuel i mean that's that would be like the the ideal reliable idle yeah and i mean and the reason you do that is

[00:24:05] Because you don't want it to die when you're flying if it dies when you're in the middle of a flight depending on where you are that can be disastrous if you're high enough if you're not at a bad angle you can come in and land a dead stick but nobody wants to do that what

[00:24:20] If i'm in the middle of the most epic inverted flat spin ever at idle and it dies and i need power

[00:24:26] To get out of that right yeah so it's it's worth spending the extra few seconds because really right it might be a minute or two it doesn't take a long time to tune these but it's better to do that and and get it done correctly so you're flying with something you can trust it's one of those things the more you put into it the more you get out of it because if you don't do this you can very easily crash which nobody wants so the more the more time you spend making sure everything is done correctly same with pre-flight checks same with every little thing that we do

[00:24:57] It's just good to make sure you give yourself that little extra insurance that what you have is is right what you have is going to perform the way it's supposed to perform and not let you down by means of costing you a bunch of money because it's now re-kitted right yeah exactly yeah so yeah a

[00:25:16] Good a good reliable idle is is is high on my in fact i would put a higher premium on a good quality reliable idle than i will getting max power at wide open throttle i put a higher

[00:25:30] Premium on that on that reliable idle yeah because usually you don't die when it's at full throttle

[00:25:34] Well i mean let's let's think about the situations where you would be at full throttle takeoff which yeah that could be disastrous if it dies at takeoff but generally speaking the the time that you're going to be at low or idle could potentially be the most disastrous if you lose power now arguments could be made one way or the other but yeah i put a higher premium i i'll put a little more effort into getting a good idle than i do at getting max power just what

[00:26:06] I do yeah i think i would agree with that without digging too much into it but that makes sense to me

[00:26:12] Yeah so once once i've got a good a good quality idle the very last thing i'll check is the transition and that's just simply moving the stick from idle to wide open it should make that transition it should it should speed up smoothly it shouldn't it shouldn't hesitate it shouldn't you just want a good smooth transition from low power to high power and if you've got a

[00:26:43] Good idle if it's idling well chances are the transition is going to be pretty close and it's going to depend on the manufacturer of the engine getting back to one needle affecting the other in the in the transition phase that's where sort of on most carburetors both of those needles will sort of play together so i try not to make my adjustment on just one needle for transition purposes unless you have one of those really really fancy three needle carburetors

[00:27:16] That has a needle just for the transition but i'm not going to talk about those i've never heard of those so yeah they're not very common but anyway so if if at idle i i go to full throttle and it hesitates and and runs rough and kind of sputters and doesn't seem to want to get to full throttle right away but eventually makes it it's probably on the lazy or rich side because it's lazy it's being lazy about getting to it's resisting i don't want to go to full throttle

[00:27:49] It's probably probably rich and and what i'll do in that situation is i'll lean both needles a tiny tiny bit each and i try to go i don't want to say equal amounts because usually an eighth of a turn on the low speed needle does not equal an eighth of a turn on the high speed yeah i sort of play with both of them a just a tiny little bit at a time and it takes a little it takes time to get it right if it's not right but but generally that's that's how if it if it's lazy on

[00:28:24] The transition it's probably on the rich side on the other hand when you move the throttle to wide open and it immediately goes wide open and then dies now chances are it's lean probably on the low end in which case i'll richen up the low end so when you say a tiny bit on the needles are you talking

[00:28:42] About like a sixteenth of a turn a sixteenth or less yeah or less because you've because you've

[00:28:48] Already got a good quality idle right you don't want to mess that up and you've already tuned the high speed needle so you don't want to you don't want to make that overly lean right that's why whenever i tune the high speed needle i leave a little extra like i'll i'll tune it for for i don't want to say max rpm but i'll go to max rpm and then i'll back that needle off towards the rich side to give me a little bit of a cushion to be able to fine tune the transition if need be so then like

[00:29:17] When you're flying and you go to unload the engine and you're not sitting there with so much pressure on it just not actually moving through the air does that yeah like does that have to come into consideration when you're tuning it do you go maybe do you does that lean it out does that reach into that how does that work when you're actually flying in the air when when you

[00:29:39] Know now that you have the airplane moving through the air and you don't have that that that load if you will on the engine like as if you were restraining it on the ground the engine will free up and it will usually gain up to four or five hundred depending on the engine and the prop and all that and the speed and all that but it will gain rpm in the air but if you've tuned it correctly on the ground the needle the needle setting should be optimum for

[00:30:10] Any wide open throttle setting so yes the engine will usually pick up some rpm in the air but if you've if you've tuned it correctly on the ground that will not be a problem and like i said on the high speed i always always and i can say always attune on the on the safe side i'll get max rpm or max performance and then i back it off on the rich side minus a few hundred rpm as kind of a safety margin to allow me to fine tune that transition and then also to you

[00:30:46] Know there's just no reason to extract max power i mean most of our airplanes are overpowered today anyway yeah there's no reason to to run them that hard these modern engines a lot of them are what we call abc construction aluminum brass and chrome so it's an aluminum piston in usually a chrome lined brass sleeve right abc okay and how they develop their compression is basically it's a friction fit between the the piston and the sleeve especially at top to the

[00:31:22] Center so they the the engine most of engines today don't use rings for compression they just really have a very very tight fit yeah so when when the aluminum piston is up to temperature aluminum expands at a greater rate than steel does so as that engine comes up to temperature that that aluminum piston swells because of the heat and then forms that that tight seal at the top that will help you create compression so is it tapered then or how does

[00:31:52] That work it is yep yep it's called pinch yep it's called pinch so the the sleeves are are exactly like you said they're tapered i mean we're talking very very very small like less than thousandths of an inch right but it is it is tighter at the top than it is at the bottom so yeah as the piston moves up and when everything is at the proper temperature it gets tighter tighter tighter and that's what makes that compression instead of relying on a steel ring or

[00:32:23] Well a steel ring yeah so because that's a mechanical a aluminum riding on chrome chrome there's wear right so if i can if i can tune the engine so that it runs cool and helps to prevent that wear and make it last longer that's what i'll do well especially

[00:32:46] Because all the lubrication comes from the fuel it's not like a regular car engine that has an oil pump and oil built into it right from how i understand it the oil that's in the fuel actually goes not only in the like the upper cylinder but it actually goes along the crankcase

[00:33:02] Too and lubricates all that as it's going in right yeah because the the crankshaft is hollow like like we talked about an episode or in the in the first part of this episode yeah so the fuel is carried down the the hollow cavity of that crankshaft and then the spinning action sort of slings the oil all over those bearings and whatnot yeah we don't we don't have a wet sump oil system like modern cars do with a pump that can circulate the oil yeah it depends we depend on the oil that's in the fuel to do all that lubrication so why not run it just a little

[00:33:35] On the rich side so that we can get everything lubricated yeah so i guess talking about kind of care on that one then because it's it's better to run them rich it'll make them last longer what are some other things like you need to know to take care of an engine like that so we're

[00:33:52] Going to talk about fuel here in a little bit but before we do that i'll just say that the fuel that we use it's methanol i mean it's alcohol alcohol attracts water and of course water and steel don't play well together steel rusts in the presence of water and various other

[00:34:15] Factors so because of that we want to try to get as much of that alcohol or fuel out of that engine as we can when we're done flying for the day the way i do it is i idle it dry so basically at the end of the day and i'm done flying i'll go ahead and empty the tank with my with my fuel pump and then i'll disconnect the fuel feed line well i've already done that because i'm defueling it i'll leave it disconnected put the put the glow heat on set the throttle to idle and i'll fire it up until

[00:34:49] It just will not run anymore and then once i've done that i'll i throw some after run oil in there and then flip it over a few times to get that oil on all those parts because i don't want i don't mostly it's the bearings the crankshaft rides on bearings in most of these engines and those bearings are steel and i don't want those to rust so i'll try to get as much of that fuel out of there so that i'm not attracting water to the steel and then also get

[00:35:20] Some lube on it so a couple weeks ago we talked about one of the airplanes i have then that's the motors tightened up on it i'm guessing then that's what's happened on the inside because i've not maybe actually yeah i guess i can't say that for two or too sure because i haven't ran this one yet but it's it it spins it's not locked up but it's just very tight compared to some of the other ones i've seen so i'm guessing whoever ran that last probably didn't put the after run oil on it then and then that's kind of what's happening is that that moisture is kind of getting pulled out

[00:35:53] Of the air because of what was in there maybe maybe so maybe yeah so like i i know the engine you're talking about and i felt it too and my gut instinct is that the bearings are in good shape and the reason i say that is because even though the engine is tight to turn over and there's resistance to turning it over when it does spin it spins smoothly like there's no grittiness there's no yeah

[00:36:24] Catching or anything like that while yes it's physically tight to turn over i i feel like the bearings are probably in good shape either that or they've seized up solid and i'm spinning the crankshaft in the bearings which that could be i don't think it is because it would feel much tighter my guess is that they may have left fuel in it that that's a possibility or maybe they're using a fuel that's more castor and castor over time sort of it's hard to describe what it does but it

[00:37:01] It sort of gets sticky and gummy almost like an almost like a glue and if if allowed to sit in an engine for a lengthy period of time it can cause that sticky hard to turn feeling luckily that that caster will liquefy for lack of a better term once fuel is introduced to the mix again and it will start to spin freely again and that's what i think is going to happen with that particular

[00:37:31] Engine yeah so it'll just kind of work itself out then once we get it going again i think so yep i

[00:37:36] Think i think it's i think it's safe but we'll see yeah so i i didn't mean to get you off topic sorry

[00:37:42] You were talking about the after run oil and you said you you put it in your engines when you're done running it where how do you put it in your and i'm like where does it go in oh okay yeah so

[00:37:53] Well let me before i before i talk about where i squirt it after run oil is just basically a lightweight oil and there's there's some on the market that's pre-made that you can buy there's there's lots of home brews that people make myself i i've got the there's my own mix that i like to make i use a 50 50 mix of marvel mystery oil and atf automatic transmission fluid i mix those two together and it's a nice lightweight oil that doesn't evaporate like wd-40 can so and you don't

[00:38:27] Use a lot so a little should last you a long time right yeah it doesn't take much i mean i mean more is certainly not going to hurt anything but yeah it just takes a few drops and the way i do it is i open up the carb and i squirt however much in the carburetor and then if i'm if i'm really no i'm not going to fly this airplane again for a while i'll go ahead and pull the glow plug and squirt a few drops down into the combustion chamber and i'll put the plug back on and i'll flip it over quite a few times to get that oil sort of distributed throughout the engine and then it'll be it'll be good

[00:39:00] To go for the next time i go fly and so do you cover the carburetor like you're priming it or just

[00:39:05] Let it go open nope nope just i just leave it wide open and then flip it over a bunch and then when i'm done with that i'll close the carburetor well that doesn't sound too hard really it's not it really unless unless you have a fully cowled in engine and then it gets a little more complicated but you can sort of accomplish the same thing by squirting it down into the exhaust try to get the airplane at an angle where you can do that you can physically get that and then you can you can flip the engine over and you can accomplish it that way too certainly

[00:39:37] Much easier to do on a on an engine that is exposed but it's very important you should figure out a way to do it if you can yeah talking about caring for the engine when you're done flying put some oil in it to keep it keep it fresh and keep the keep the rust ease away there's other things you can do to take care of them too right you want to make sure the residual fuel is out of the engine either by my method idling it dry or some other methods some people like to pull the glow plug and turn the

[00:40:12] Thing upside down and flip it over until it flips dry whatever your method get that unburnt fuel out of there some guys i've seen them when they get home they'll fire up a compressor and blow the engine out that's that works too whatever method you want to use but try to get all that raw fuel out of there because you don't want it drawing moisture to those bearings and then once you've done that keep them clean i mean these these engines they they have these cast end fins for a reason and when they're when they're clogged with grass

[00:40:47] Clippings or old oil that's gotten caught in there and dirt has been attracted to it and it's we depend on air to flow over these fins to help keep these engines cool because they're air cooled right and you get a little bit of cooling from the from the fuel and oil that that's in the the oil that's in the fuel but mostly they're air cooled so those fins if they're blocked or if they're covered with gunk or whatever they're not as efficient as keeping keeping the engine cool as a fresh clean engine is so not only do they look better when

[00:41:20] They're clean they're more efficient at keeping themselves cool which a hot engine is going to wear out faster than a not hot engine so yeah so those fins that are kind of like a a built-in

[00:41:31] Radiator exactly yeah it's just made to dissipate the heat that's created yep that's exactly right

[00:41:39] Okay okay so yeah keep them keep them clean i mean i keep a i've got a little toothbrush an old toothbrush in my flight box that if i if i see some gunk on the engine i'll brush it off and then ever how often whenever it whenever it's needed i'll take take the engine off the airplane disassemble it and give it a good cleaning and we'll talk about

[00:42:02] That in some other episode yeah and actually i guess not only keeping it clean is going to make it last longer but it's also going to keep everything around you clean so like if you store them in your basement or if you have to transport them in your car you don't want grease all over the place i i would probably get in trouble if i brought our car home with a big grease spot and in the in the back of it or something so just once again kind of keeping that stuff clean makes it last longer makes it look nicer like you said and it will help you not get

[00:42:35] In trouble too i guess with the misses right i tell you what something else that'll that'll keep

[00:42:40] You out of trouble is these these big mufflers they have a it's hard to get all the fuel out of them i mean i don't know about you but i don't like i'll have an airplane sitting on my little rack here for months and i will have thought that i have gotten all the fuel and all the oil out of it and then a couple months later then there's a drop spot on the floor yeah it's like yep where the heck did that come from so one one more little tip that'll maybe keep you out of trouble is to wad up a a small bit of paper towel and plug the exhaust

[00:43:14] Yeah cheap insurance very cheap very easy very quick and yeah that's that's a good idea too so especially if you're carrying them downstairs or anything like that too if if i like i store mine in the basement so getting down here you have to walk on on carpeted carpeted steps and then carpeted basement to get back to the the hobby room and yeah so that's that's a that's a good

[00:43:37] Tip i like that idea so the stuff i i use to clean my airplane i get at sam's it's called spray way glass cleaner it's like this aerosol cleaner it does a great job of getting like the nitro fuel residue off the airframe stuff so i always have a bottle of that with or a can of that and a bunch of paper towels that i take to the field with me yeah so yeah one of the last things i do is i'll take a piece of paper towel wad it up and stuff it in the exhaust so i'm not dripping oil on the

[00:44:04] Stairs bringing the airplanes in yeah smart and probably learn that the hard way huh i did

[00:44:13] Yeah most of most of the things i've learned over the years has been the hard way

[00:44:19] Yeah i try and listen to other people when they tell me to do something if it makes sense so and and that's one thing i did notice too like this airplane of yours that you still have over here it's it's got that oh god it didn't drip on your floor did it no no no no no it didn't but it does have the the paper towel in the exhaust okay so yeah or in the muffler so i kind of laughed at that yeah yeah that's why yeah and that well i i kind of figured that's what it was and that makes

[00:44:47] Sense so yeah good idea yeah so i talked a little bit about the stuff i take with me to the field the the cleaner and the paper towels and stuff so what are some like tools you would

[00:45:01] Need if you decide you want to get into the glow side of things if you just have electric and you need to go the next step because that it kind of is the next step what are some special tools for a nitro engine that you would need if you don't have it already well chances are you've

[00:45:18] Already i mean if you're flying electric you probably already have a lot of the a lot of the tools you're going to need but specifically you'll need a glow plug wrench to pull the glow plug out of the engine which is a 5 16ths in most cases deep well socket or especially a design tool that you can get at the hobby shop and then like i said pretty much everything else you're already going to have maybe a piston locking tool is handy if you ever need to disassemble the engine and that's basically just a a quick little tool that goes into the where the glow plug goes and

[00:45:50] It's got a shaft that goes down there and makes contact with the piston so that it kind of locks the crankshaft in place so that you can perform maintenance on the engine and that's really it everything else probably if you're already flying you're going to have a prop wrench some allen wrenches and stuff like that so what would the the piston locking tool kind of help with i mean like what what would you need that for yeah so most most modern engines the

[00:46:23] The propeller i don't want to say hub but the but the thrust face if you will that the that the propeller gets butted up against when you bolt it on those are usually pressed on and they do make special pullers for that but if you have a piston locking tool sometimes you can use a most times you can sort of use a strap wrench and turn against that with the with the crankshaft

[00:46:52] Locked as long as it's not that okay i understand what you're talking about the part that goes behind the propeller right right okay so not the not the prop nut that holds the propeller on so the propeller is completely off and it's the piece you see back there that kind of has the the knurling on it to hold on to the the propeller okay yep i gotcha so that that that

[00:47:15] Piston locking tool is sometimes helpful in cases like that is just just one method to lock the crankshaft in a in a in a position that allows you to put torque on that particular piece of the engine so like i i have one but i can't remember the last time i used it because i have since bought the tools i needed to do the job correctly so but but anyway that aside from

[00:47:49] That most of the other tools are going to be fairly standard and if you're already flying electrics

[00:47:53] You probably already have them okay what are some other like special considerations and with the nitro do you like i know with carburetors sometimes you have to clean them do you need

[00:48:04] To worry about doing that at all you can like so we we fly on well i fly mostly off of grass fields right and so occasionally the propeller may get into some grass and throw some of that into the carburetor and usually grass will just get eaten by the engine without without too much fuss but the dirt and the dust can accumulate around needle seats and and things like that and and otherwise get into the the adjustment mechanism the high-speed

[00:48:40] Low-speed needle and in cases like that the the only real way to to fix that is to clean it if

[00:48:47] That makes sense yeah what what's involved with with cleaning it well usually you can you can do it

[00:48:53] Without disassembling the carburetor and the way i do it is i'll make a note of the current needle settings so what what that means is without applying a lot of pressure i'll take the high-speed needle and i'll thread it all the way in until it stops and i'll count how many turns that was and then i'll back it all the way out and then i'll do the same thing for the low-speed needle and then with with all those orifices now completely open i can usually take my fuel pump

[00:49:26] And hook up the to the fuel nipple of the carburetor and sort of pressurize those orifices with raw fuel and usually it'll blow any of that gunk out of those orifices and like i said that that's one way you can do it without disassembling the carburetor and that's really the only thing that will ever really need cleaning aside from brushing off the loose stuff on the outside so it doesn't get sucked onto the inside but but yeah you can you can do that usually

[00:49:57] Without disassembling it now if you've got something really stubborn in there then yeah you'll you'll have to take the carb apart and figure out what the what the blockage is but understand that if it gets to that point you really need to understand how the carburetor works so that you don't do any damage when you're trying to when you're trying to clear it

[00:50:20] Yeah so if you're not comfortable doing that probably reach out to somebody else that is

[00:50:24] Right just to be safe and you'll know like if you have you'll know if something is going on with the carburetor because one second or one minute one flight whatever it was running fine and now all of a sudden i can't seem to get it tuned correctly or now for some strange reason it's running really really lean when it was perfect before usually that's your first sign

[00:50:45] That there's something going on with the carburetor yeah and so before you you clean them though do you

[00:50:51] Take them off the engine it depends like if if i can perform that operation without getting fuel on bare wood and make just generally making a mess like if i can stuff a bunch of paper towels around to do that i'll do it in the airplane without removing the carburetor but if it's in a position or if it's in an airplane that doing this is going to pool raw fuel and oil are going to pool in the engine compartment or whatever then i'll i'll either take the engine off the airplane or i'll if i can i'll take the

[00:51:26] Carburetor off a lot of these carburetors are are they're bolted onto the crankcase and then there's an o-ring between the crankcase and the carburetor and that serves two functions honestly it's it's number one to seal so you don't have an air leak between the carburetor and the and the engine but it also serves as kind of a an insulator if you will so you're not transferring the heat from the crankcase to the carburetor and boiling the fuel and stuff like that so

[00:51:57] Okay if you have yeah if you have to take the carburetor off be really really careful about that o-ring because it is a pretty important little piece of the entire operation so like

[00:52:08] Do do carburetors wear out i mean do you have to replace them yeah they do if you're if

[00:52:15] You're heavy-handed with with your needle valve operation if you if you're running it in and using too much force to like if you're taking measuring your needle settings and you run that thing in i mean these parts mostly the orifices and needles are brass so they will swell right so if you run that needle in you're you're damaging the seat and and this sort of thing so occasionally you if you're in the hobby long enough and you and you do these sorts of things then yeah a carb replacement will be necessary and it's it's

[00:52:46] Simple enough to do most carbs are either bolt on with a with a couple of screws or they have like this cool little pinch block with a nut and basically remove the screws or loosen up that nut and pull the carburetor off being careful of the o-ring and usually a new carburetor

[00:53:03] Will come with a new o-ring so then like if you have to replace the carburetor though because something's wrong is that most of the time because something you've done to it or i mean do they actually wear out at like faster rate than the actual engine does itself no no they can they can

[00:53:18] Wear out i mean because like for instance this this carburetor i'm looking at here on my old irvine 40 it's a it's a rotary it's a barrel that rotates inside the so over time if you've got enough use on the engine enough open and closing cycles they'll wear and then you'll develop an air leak around that that barrel and then air leaks are not good for tuning so yeah yeah then simply due to where you'll have to replace it oh okay well that's interesting i i

[00:53:49] Always kind of figured carburetors being as simple as they are for something like that would not wear out but i guess yeah a lot of times these engines though will last like a long long long long time

[00:54:01] Yeah chances of of most modelers running an engine to the point where you have to replace a carburetor because of wear just from use are i would say rare more often than not you'll have to replace a carburetor because i've ham-fisted putting it together or whatever or because

[00:54:22] You bought it from a flea market or from a swap meet and you don't know the history and somebody else did that to it and that's why they got rid of it right right so is there any way like obviously if you're bringing that up so if you're at a swap meet or something and there's a box full of engines you can usually tell right by by spinning them how much compression they have and and the bearings and all that is there any easy way to check a carburetor or not unfortunately there's not an easy

[00:54:52] Way i mean you aside from just moving the throttle arm making sure that the thing moves that's obviously the first test and then you could if you really really wanted to test them you could have like a piece of clean fuel tubing with you and take a length of that hook it onto the the inlet nipple of the carburetor and then the other end to your mouth and blow through it and then gradually open the throttle and you should gradually be able to blow more and

[00:55:22] More air through it and then when you close the throttle it should close off that that that that should that valve should close off the airflow you could do that test but otherwise yeah until you've until you've heard it running you're never gonna know for sure yeah so is it best to stay away from secondhand engines then or if you kind of know oh motors it's no i love seeing boxes of engines at swap meets i have i have an addiction i mean i've got a whole shelf of them here and then

[00:55:54] I've got a whole shelf of them back there i mean i love when i go to swap meets that's like the first thing i go to i can look for the guy that's just got a bunch of old engines on his table and then i'm like in heaven that's my spend the whole time there that's funny yeah i could yeah you do have a lot of

[00:56:08] Extra engines so i don't think you're ever gonna have to really worry about running out no no i keep

[00:56:15] Getting more i just i just ordered two more yeah well that's because those two have to match

[00:56:23] They do but that's that's another topic i don't want to get off too much on it so fuel what kind of what kind of fuel does do these nitro engines use well we we i touched on

[00:56:38] It before and it's a it's a it's a glow fuel like for our we're not talking about gas engines we're talking about glow fuel engines and it's a fuel that's basically got three parts it's a it's methanol some lubricant of some kind oil and a little bit of nitromethane in most cases so that's that's what it is it's alcohol oil and nitro in that order so what is the like why what does each one do yeah so alcohol that's what's required to burn and keep the

[00:57:15] Whole suck squeeze bang blow process going right we need a little bit of oil like we mentioned before these engines don't have a wet sump they don't have a a crank case full of oil for lubrication so we get the lubrication out of the fuel so that's oil either castor or synthetic most often it's it's a combination of both of those and then and then some nitromethane in various percentages not always though there is some fuel out there fai blend that has no nitromethane

[00:57:47] And the engines seem to run just fine on it so what would the what would the plus be to that

[00:57:53] So nitromethane it's it's kind of like nitrous oxide it it adds density to the fuel air charge so that it it's hard for me to explain i think you probably understand it better than i do because i we were talking about it before but it it basically allows the engine to run a little bit cooler by allowing you to have a little bit more of that of that oxidizer oxygen in this case

[00:58:32] In the intake charge that makes the engine a little more efficient well and the the kind of way that i

[00:58:39] Understand it too so that the nitromethane carries its own oxygen so with it having oxygen in it you don't have to rely as much on the oxygen from the air outside because really the air we breathe is mostly nitrogen but the oxygen is in or that is in it is what helps the the fuel burn so with not having to have so much of the the atmospheric air pretty much in the

[00:59:12] Cylinder gives it more room for fuel so if you get more fuel in there then that is why you get more power out of it kind of like the kind of like the the nitro funny cars they dump a lot of fuel through there because they have such a high level of the the nitromethane that they run that that oxygen pretty much is is flowing in in that as opposed to the air that we breathe so you can

[00:59:42] Get a lot more power out of it that way so that's what that's how i understand what the nitromethane

[00:59:46] Does to it yeah yeah and that that was a very much easier explanation than mine

[00:59:56] Well thank you so that's yeah that's my understanding right or wrong i don't know but

[01:00:01] That's that's kind of how i know i think i think that's right but like i said your your explanation was much easier to understand than mine to talk a little bit about the the oil that's in our fuel i said there's castor and and then there's synthetic and most fuels are kind of a combination of the two but there are some purists out there who still who still blend to their own fuel because they like straight up castor i guess i don't really have an opinion i i try to

[01:00:33] Take care of my engines so i i don't have issues with carbon buildup and varnishing and and that sort of thing yeah but there are those out there who swear that that castor doesn't it's viscosity doesn't break down with heat the way synthetics can so that's why most manufacturers blend the two castor and synthetic oils together to get the benefits of castor but kind of a downside to castor is that it it kind of leaves a brown varnishy film on stuff especially

[01:01:07] When it gets hot gets baked on and it's really really hard to get off it just looks bad and it does it does carbon up a little bit more i think than the synthetic stuff does but either way if you stay on top of the maintenance and put your engines away properly you won't you won't really have any

[01:01:25] Issues with that yeah so pretty much the easiest thing is just kind of buy whatever airplane fuel there is because i know there's a different nitro fuel for airplanes than there is for like rc cars too and that all if i remember right just depends on the amount of nitromethane that's in with it i don't know if there's any difference in the oil or or the methanol or whatnot but i know it's a

[01:01:49] Different percentage of nitro yeah pretty much the standard the standard fuel that most model airplane guys are going to use it's going to be some either five ten maybe fifteen percent nitro and most of those fuels come with a fixed amount of oil in them usually somewhere around eighteen percent oil the car guys yeah i think they use twenty percent nitro and maybe a little bit a little bit less oil maybe i don't know but yeah there's whatever is being sold out there for airplanes is generally speaking is it's a pretty good bet that it's safe for your

[01:02:25] Airplane engine yeah it'll it'll pretty much cover any manufacturer's recommendations for what the what to run through it so you'll be pretty safe i think the last thing i'd like to barely touch on because we're running long on this one too okay engine break-in so let's let's say instead of buying an engine at swap meet you buy one brand new you don't just want to go out start it up put it on your airplane and and run it what's the what's the normal process for breaking an

[01:02:58] Engine in and why is it why does it need to be done right so like like what i was talking about

[01:03:05] Earlier most modern engines are that abc type construction so they they require or they depend on that that precise fit of the piston in the in the sleeve and to achieve that it has to be broken in in a very very specific manner and the manufacturer's instructions will do a fantastic job of explaining it but i'll do i'll try to do a quick one the parts have to be at the proper operating temperature to break in properly because that's the operating temperature that they're designed

[01:03:36] To run at so that's the operating temperature that the tolerances are designed to run at so the break-in procedure for an abc engine is really more about temperature than it is about wearing the parts in so the engine has to be run at its proper operating temperature for the parts to wear in properly if if the engine is is run too long at too cool a temperature the parts are going to wear prematurely and you're going to have a poor running engine in a short amount of time whereas

[01:04:09] Somewhat more standard construction that's not quite as common today a piston with an actual compression ring on it that actually depends on that physical wear in of the ring to the sleeve or the or the piston or the cylinder wall and and that requires a lot of lubrication during that process so we run them really really extra rich with really no no regard really to the temperature because we're not worried about breaking those in at that very very precise operating

[01:04:42] Temperature range so the two different ways to break them in and your engine manufacturer will tell you how they want you to break that engine in and you should follow it to the letter

[01:04:55] Yeah and i guess i did say something about brand new engines this also applies to a rebuild engine so if you resleeve a if you resleeve your piston or you resleeve your cylinder and put a new piston in it's the exact same thing treat it like a brand new engine because pretty much it is that's exactly right the the worn out pieces have been replaced and and the new pieces that have to fit nice and tight have been replaced and and and it needs to follow that that same procedure so yeah these can be rebuilt if if you do run into a a place to where it's not running right

[01:05:32] You don't have compression something's wrong the engine's not junk yeah the engine's not junk it's fixable and it's not actually that difficult no it's not i don't want to get into that in this one okay i think that would be a good another episode to kind of talk about how to rebuild one of these engines yeah so yeah maybe we can do that sometime but for now i think i've covered everything i want to cover do you have anything else you want to say

[01:06:01] No no i think i think we've kind of given a good general overview and why these things are so

[01:06:06] Awesome yeah we've got into it a lot more than i expected to so sorry no no no it's fine i enjoyed the conversation i don't know if anybody is still listening other than me right now but that's okay well i'm listening well that's that's true but yeah so i guess for that i'm going to end this one now thanks for listening everybody i'm ron and i'm tom until next time

[01:06:32] Goodbye see you we hope you enjoyed this episode of the rc plane lab podcast for topic suggestions to ask questions or to give any feedback connect with us at rcplanelab.com or email us direct at either ron at rcplanelab.com or tom at rcplanelab.com you can also text us or leave us a voicemail at 818-351-9846 please subscribe rate and review us on your favorite podcast app until next time may your landings be gentle