It is easy to take out the baffle. Only took a couple of minutes. Same thing with popping off the limiter collars. They come right off without any problems.

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How do you keep the low end needle valve from "walking"?

As suggested here, I ended up removing the Low Speed needle altogether and putting a little locktite BLUE on it.

I was afraid that the Locktite would break down because of the heat, but it seems to hold up.

I've since also removed the limiter pin.

Mine never crept around. It always stayed where I put it.

Do you mean you put the lock tite blue directly onto the threads of the low speed needle valve and screwed it back into its hole?

On a couple of Evolution engines I have, it has crept from day one.

Exactly...

Count the turns from fully in, before you do this.

And remember to be GENTLE when it bottoms out so you don't damage the needle.

trt

I took the heavy blue limiting / finger adjustment ring off the low speed needle valve. Mine have never crept. That ring could cause creep, i adds a lot of mass to that needle increasing the chance that it will creep.

That's what I did on my 2 Evo's...a .46NT and Alpha trainer engine...(so far-so good )

I did notice though, before I took the blue collars off, the weight of it and the black pin would cause it to rotate w/ vibration.

With the heat of normal engine operation the needles "walk" quite a bit, especially the low end.

At our club, this was driving the engine experts nuts as they couldn't understand why the engines kept going out of tune on people's planes when using the Evolutions.

A slight variation in production tolerances could add to the problem...(slightly larger hole / slightly smaller O-ring, etc. )

Maybe the throttle barrel spring needs to be stretched out some.

Yeah I tried that on my 1.00NX but that doesn't seem to be the problem. The needle visibly "walks" in use, as you move the throttle. You can see that it doesn't return to the same position after you've flown the plane.

The PTS .455 engine also walked out of the box, and fortunately we were able to spot it. It wasn't a spring problem.

Once the walking was eliminated the .455 has run like a champ.

Just thinking...hypothetically speaking...what if you took the idle needle out and soaked it w/ o-ring, in oil? That would make the o-ring swell up some, huh? Maybe that would make it a tighter fit after it was put back together?
You'd clean all the oil off first and re-lube w/ fuel during re-assembly.

edit: Never having the need to dis-assemble one of my Evo carbs, I don't even know for sure there's an O-ring on the low speed needle but it feels like there is one when I turn it to adjust it...

There are two (or three?) O rings on the low speed needle.

That may work, but I would be worried about it loosening after a few flights. The rings get wet with glow fuel in use.


The loctite solved the problem of the needle walking on both engines, on the 1.00NX I have other problems though.

The PTS engine is wonderful now... It was easier to get running reliably than say the T.H. .46.


I've been fighting with the Evolution 1.00NX all season. I didn't know about it needing a 4 stroke plug until recently too.


In contrast a new O.S. .46 AX and LA both started out of the box and required relatively few tweaks.

The Evolution .455 PTS did fairly well until the needle started walking. The Loctite fixed that. On the fifth tankful I had a reliable engine.

A new T.H. .46 was a bear for the first gallon of fuel then settled in perfectly, and became easy to adjust after an additional half gallon.

I agree that the .455 is a better engine than the .46NT. Mine it totally reliable. I got it used. My .46NT ran slightly rough on the first tank of fuel, but was running great after that. I never had any problems with it, though I did notice that it kept getting smoother and stronger the next 4 or 5 tanks of fuel. Remember, these are chromed sleeves that are breaking in instead of nickel. It could also have something to do with the pinch between the OS and Evo engines....maybe, but I'm betting it is the chromed sleeves as they are much harder.