My mentor moved!! I need to re-adjust my throttle linkage. I know there is a way to swivel the entire needle valve assembly that is the nearest the front. I am not sure which of the set screws to adjust. There are two "allen" head screws, one on the blue ring and the other on the silver. Which one? I need to adjust because the clevis and push rod are rubbing on the motor clamp screw.
Thanks

The silver one

The blue ring (if I remember) is actually a throttle adjustment limiter that prevents you from over-tuning the engine. On mine, it actually prevented me from achieving the setting I needed. Loosen the allen bolt, slip it off and forget about it.

Actually DO NOT "forget about it"...

If you do this the needle valve will turn with engine vibration as the engine warms up.

Instead remove the limiter and pull out the metal pin, then re-install it.

Before you do re-install it, also pull out the clip and bend down the clip arm a bit more to apply more pressure.

The limiter holds the clip in place so that is another reason to keep the blue aluminum limiter w/o the pin.

There are two different limiters.

The one that the gentleman asked about is in the area of the low speed needle.

The one that you cannot completely remove is the remote high speed needle.

Re: Needle.

Yes the high speed is what I was talking about.

I've never have needed to remove the low speed needle, as all you have to do is loosen the cap/grub screw and then adjust the engine.

Since the low speed needle tends to "walk" was well, it is advisable to adjust the engine and leave the collar in place along with the pin.

Better still tighten the blue collar/limiter against the engine as you tighten the grub screw to provide more friction to prevent the low speed needle from walking.

I took both of mine off and it runs fine. No vibration problems. The only problem so far has been the OS 8 being too cold.

Guess I got lucky too? The 2 Evo's I have don't have a walking idle needle after I removed the collars.
They will turn very easily, and at first I thought it might be a problem, but so far...no.

Most of the posts here about loosing tune, or changes to the engine once in the air then having to retune, involve the "walking needle" problem.

We've have had a number of PTS P-51's and other planes with Evolution engines at our field that exhibit this.

Our resident senior engine "expert" (he has written several books on R/C engines) learned this the hard way helping me to get my plane flying.

Now he advises these changes with all Evolution engines.

On my high speed needles, I took them out and just kissed the little roll pin with the dege of a Dremel cut off wheel...
When I put it back in (after a good cleaning of course ) I bent the spring clip down to provide more pressure on the ridges.

I have noticed on occasion that sometimes if the spring clip gets bent out of alignment, it will allow the needle to "self adjust"...
I just put a small piece of fuel tubing over the clip...

Heh, that's one fix that works.

The low speed suffers from this as well.