bradyb

Hey folks please help me. I have a sweet 50 size p-40 ready to go but the new Evolution .60nx I put in the plane is not happy. I broke it in fine on the test stand and now that it is in the plane I can't keep it running at full throttle. It starts out fine but at full throttle out peaks and then dies, just like you were leaning out the high speed needle too far. I have tried the usual things like a different glow plug, setting the needles back, etc. The main difference being the engine is now mounted upside down. I can prime it and start it just fine but it eventually runs out of fuel. I am running with out a muffler gasket, the engine only came with one and it was ruined after I pulled off the muffler to instal it on the plane.

What would your suggestions be? I'm thinking I should pull it out and put it back on the test stand but I know the blind nuts are going to give me hell. My next step would be to check all the fuel lines again and maybe put a new muffler gasket on.

FYI, the carb is slightly lower than the tank and I'm running a third fill line.

proptop

My Feedback: (8)

If it ran well on the test stand, then it most likely is a tank installation or plumbing problem.

Check all the lines for splits or pin holes...make sure the tank is perfectly clean. (I once had a very small sliver of plastic from the tank get stuck in the clunk...restricted fuel flow...drove me nuts...)

It sounds like maybe it's sucking air from somewhere?

The muffler gasket shouldn't make that much difference...but...to be sure, you can use high temp. RTV silicone gasket maker / sealer.


Another thing to think about is...
You said that the carb is slightly lower than the tank.
In those instances, it's possable that you need, or needed to lean the high speed quite a bit (compared to where it was on the test stand ) to keep it from being excessively rich.

When you bench ran it, the carb was probably lower than the tank?

If all else fails, give 'er a piece of chocolate...

tschuy

My Feedback: (1)

I'd have to agree with proptop. Check the plumbing of the fuel system to ensure that there are no pinches or holes in the lines. Tank placement has a pretty good impact on how the engine runs as well. If the tank sits too far below the carb it will run lean. A quick test is to start the engine a flip the airplane over on its back and see if it has any affect on the engine.

proptop

My Feedback: (8)

One more thing...
Where is the low speed needle set? If it's in a bit too far, it will effect the high speed needle as well.

bradyb

The fuel lines are new but maybe I knicked one with the dremel. It could be dust from the dremel as I trimmed out some things to fit. But that doesn't make sense because it runs great at mid to low rpms.

I have it running so rich that it's spitting out fuel all over. Something somewhere is either slowing the flow of fuel or not giving enough pressure to the tank. The pressure fitting off the bottom of the muffler is on the bottom of the muffler, would there be a problem if the thick caster oil is being sucked up by the pressure line? Would that clog the pressure line?

Stuff like this makes me insane.

bradyb

I've had the low speed needle all over the place. I even turned it out passed the factory stop thinking that the .46 carb wasn't providing enough fuel for the .60.

TedMo

What did you just say, 46 carb not giving enough fuel????????

bradyb

At first glance the .60nx is essentially a bored out .46, that's why it only weighs 17oz. With a closer inspection it does appear to have a larger carb, I was wrong.

bradyb

Check out what was in the tank. It looks like part of the gasket was sucked back into the tank from the muffler.

I'm guessing I have something clogged somewhere. Should I pull out the carb, disassemble it and clean it? Where should I check for blockages?

I'm thinking I should just get some new silicone lines too.

bradyb

Well, I'm disassembling it now. Anyone know how many turns out the low speed needle is set at from the factory?

proptop

My Feedback: (8)

IIRC, there should be a gap of approx. 1mm between the tip of the LS needle and the end of spray bar tube at Wide Open Throttle. That should be a ball park figure.

There oughta be something in the operating instructions...do you have those?

Hope all it was is a piece of debris...let us know...

bradyb

The manual is way too basic to help but I think I have it figured out when compared to a couple other Evo carbs I have. When the needle is on the rich side there does appear to be a mm gap. I'm going to mount it back on the test stand in the exact configuration that it is in the plane. I'll let you know how it goes.

Thank you Gentlemen.

bradyb

So I had a lot of fun last night.
Stopped by the hobby shop to check out what the low speed needle looks like on a fresh out of the box .60nx. At wide open throttle (WOT) the needle seems to still be a good mm into the spray bar. I went home and set everything back up on the test stand. I set the carb just as it was from the factory. New fuel lines, cleaned out tank, muffler, carb, needles etc… Started it up and it did the same dang thing, started easily but could not sustain a high RPM.

I took Proptop’s advice and screwed out the low speed needle for a 1 mm gap at WOT. It ran better and could now spin at least 2,000 rpms faster, but it still couldn’t keep the RPMS up. I noticed that the air gaps in the vent line from the muffler to the tank would start out fast and then slow down with darker fluid before the carb choked out. So I took the line off the muffler and blew through it. It was hard to blow through and what was coming out was the thick caster oil. The bung off the muffler had been sucking up the heavy oil and clogging the line. I clocked the back half of the muffler around so instead of pointing up and away it was now straight down. I also took out the baffle and made an easy exit for all the heavy oil.

I started it up and holy cow what a difference, it screams now!

So here are the required two corrections I’ve found:
The stupid .46 muffler that came with the motor had been choking out the engine. It wasn’t moving enough exhaust and oil out to make room for the higher rpms. Inverting the engine and having the pressure bung at 170 degrees was also a stupid design. Horizon really pushes the tuned pipe with the .60nx, probably because the muffler that comes with the .60nx sucks so bad (literally). Removing the baffle fixes the problem and really opens it up for the higher RPMS. It's not just an improvement for more power it is essential to running WOT.

I’ve also discovered that the carb comes from China set for the .52 engine. The .60nx and .52 use the same carb, I examined both very closely at the hobby shop with calipers in hand. In order to work for the .60, the carb low speed needle needs to be turned out to a 1 mm gap from the spray bar at WOT. You will see the low speed needle pull out of the spray bar at WOT.

All rants aside the engine really sings now. With a 11x7 it screams at about 12,500 rpms. I’m going to end up tearing the wings off this P-40.