Running in new engine.

[Colin Anderson]

I've been running in a new Irvine 40 glow engine. I understand that this should be run in at full throttle for two minute periods, allowing to cool between. I'm running it on a test stand with a small 4 oz tank. How many tankfuls before its considered run in?

Also, at present, it's a little smoky fast or slow and, to me, it seems very oily. Is this because the idle screw (factory set and, as yet, untouched) is perhaps set too rich?

[ken anderson.]

hello Colin--- I would put it in your chosen model and run it in/fly it at the same time after half a dozen flights -only then have a go a fine tuning it-----the crack one time was that all new model engines had the idle screw set rich by the manufacturer .......to save any early damage to it.....nice surname by the way ...

ken Anderson ne..1 engine dept...

[Colin Anderson]

Hi Ken,

Thanks for that; a very informative answer. However, I can't run it in the model just yet, as I'm still building it! I thought I'd run it in between waiting for the glue to dry. This is not my first glow engine, but it is my first R/C engine for my first R/C airplane and my first model in 40 years!

So, should I call you uncle, nephew or brother? Who knows, we may be related! But if so, you have my sympathies!

[GrahamC]

Well my first glow engine, four years ago was an irvine 46. I did the 2 minute run - let it cool cycle for about 2 tanks, and then flew it rich as Ken suggested. Four years later, I've passed my 'A' & "B' test with the engine, its crashed a few times, spent hours in the air, and still runs sweetly with no maintenance... Seems to have worked well!

BTW When the engine is cooling after a run, I'm told you don't want the piston at TDC - I believe that the barrel tightens slightly at the top.

[Colin Anderson]

I'll run another tankful tomorrow, then and put it aside until my model is finished.

Regarding running your engine rich in your model: did you continue to run it rich for those 4 years?

[GrahamC]

No... just for the first few flying tanks... and then into a normal state of tune. To be honest the engine seems to have been getting better... I've had a couple of 'wow that's a 46?' comments this season - when its been in a WOT 4 ARTF - unlimited vertical on a 11x7 prop.

I tend to fly once a week from spring to autumn - and I don't bother with after run oil normally. I do use after run if the engine is not going to be used for a few weeks. I use mainly Modeltechnics 10%. for fuel - but I've also used Century fuel this season.

Its a great shame they don't make the 46 any more.

[Colin Anderson]

So, is adjusting the idle screw relatively straightforward? Presumably I'd need to screw the secondary needle in?

[..]

Colin, Yes the idle screw is straight forward but take your time, and know where it was when you started so if you do have problems you can start again. And don't bother touching it untill the engine tells you too, this will be when tickover is boggy and your prop may start to run backwards. This is when the engine has settled in and is now rich.

There is lots of info on here about setting the low end needle so there is no need to worry about it .

[Colin Anderson]

Thanks Justin,

I ran another tank through today. It's still oily and smokey, but it ticks over fine; so for time being I'll leave things alone.

[..]

That's the way Colin , I'd give it another couple of tanks if it's a 4 oz tank and then lean it off on the main needle on the last tankfull . Lookup the " pinch test" on here and other forums as this will alert you to an overly lean setting. Then when your ready fit it to the airframe , after a few flights it will loosen up nicely and then it's ready for some low end needle action . Don't forget to put a light machine or after run oil in as the bearings are susceptible to rust.

As Graham says they are cracking engines they have stopped making them now so running them a click or 2 rich on the rich side of spot on will ensure a long life.

Hope this helps J ...

[Colin Anderson]

Thanks Justin,

I'll take that as good advice! I might wait a week, though, before running it up again, as I've already tortured my neighbours two days running! I don't want to make myself unpopular!

I hadn't realised that Irvines were no longer manufactured; I only bought this engine last year! As there are still plenty on sale I'd assumed they were alive and well.

[William Morrison]

It is common practice to break in (or as you may say run in) ABC/ABN engines in the air here in the States. Run slightly rich, not overly so. These designs need to heat up so that the cylinder walls expand slightly. The piston rides on a film of oil. The engines also have a "pinch" at the top (top dead center). I have a Thunder Tiger Pro .46 that is so slick inside that the wind blows the prop back and forth while it is sitting on the run stand. Yet it has plenty pinch and runs with great abandon.

Ringed engines do require a rich beginning. ABC/ABN do not need to excessively rich at the onset like ringed engines. And the engines run faster in the air than on the bench. So run in the air is the way to go.

[Colin Anderson]

Thanks Bill. I'm reasonably sure that my Irvine 40 is an ABC engine. After running several tankfuls through it I'd say there is slightly less smokiness from the silencer, but that the engine is still definitely running on the rich side - judging by the oily residue issuing from the exhaust. I can see that once I get the aircraft in the air that this is going to make the airframe a little slippery! However, the engine is in and bolted down now so further running in will continue once airborne - which won't be for awhile yet. Once I get it down the club I'll see what the more knowledgable members think when they see it. I might just get one of them to make the adjustment for me this first time.

[Shaunie]

I'm not a big believer in having the engine sloppy rich, as long as it is four stroking for the early runs and only just two stroking for the rest of the run-in it should be fine.

There can be a marked interaction between low and high speed needles on some engines. I'm just in the process of trying to get a Thunder Tiger 46 in the "sweet spot " as it four strokes too much in the midrange. As I close off the idle needle it gets leaner at the top end and I have to open up the main needle a bit or I get lean cuts at the full throttle. I'm just aiming to get a crisp pick-up with no four stroking.

It can take a few goes to get it spot on.

Shaunie.

[Colin Anderson]

Hi Shaunie,

There is only some 4 stroking when this engine is cold and at idle. Under these circumstances it will only idle for a short time and then stop. However, once warmed up there is no sign of 4 stroking; it idles perfectly, picks up without hesitation and sings well at full throttle.

[Peter Jenkins]

Colin, the Irvine running in instructions call for 2 min runs at full throttle with the engine just breaking into 2 stroking followed by a cooling period (coel enough to hold the cylinder head with your fingers). The way to tell if it is fully run in is to gradually lean the mixture, but with it still running rich, and see if the new RPM is held or if the RPM drops. It the RPM drops, open the needle valve again.

My own view on running in an ABC engine is that if you do it in the air you cannot control the full power and cool off periods accurately, Irvine state that after 40 mins the engine should be able to run at maximum RPM and hold that RPM steady. That's when you know the engine is ready for flight. At this stage you can then set up the idle mixture, turning the idle jet in by 1/8 turn and waiting to see what happens next. I find that using a rev counter helps so that you can adjust the idle mixture for max RPM for that idle setting. The next test is to check that the engine accelerates cleanly. Any stuttering with an increase in exhaust smoke tells you the idle is still too rich. If the engine dies on opening the throttle, the mixture is too lean. When you get the idle mixture correctly adjusted, even a slam opening of the throttle (not to be recommended in normal use) should just produce a clean pick up and acceleration to full power. Once the idle mixture is set - leave it alone! I find I only need to re-adjust for extremes of temperature i.e. really hot summer's day or really cold winter's day. It is not necessary to re-adjust the idle mixture for every flight!

[..]

Colin, yes your engine is ABC . Sounds like its ready for its first flight now and yes I would think the chaps at the field will assist you tuning it.

Leave the low end needle for now and get a few flights in with it then adjust. What airframe is it going in?

[Colin Anderson]

Justin,

It's going into a Piper Cub (trainer). This will be my first R/C model and my first model build in 40 years! I've built and flown C/L and FF, powered, rubber and gliders; but this was all long ago!

Peter,

Thanks for all you detailed advice. My running in process was pretty much as you've said and my engine has no problem holding steady RPM, be it maximum or lower.

[Stevo]

my engine has no problem holding steady RPM, be it maximum or lower.

Well, its an Irvine... Just keep her rich, Colin.. keep her rich. Avoid twiddling at the field... unless a major change in the weather..