I have and RCV 120 SP installed on my GP P-6E hawk. The engine was throughly run in on a test stand, and then installed on the plane where I ran two more tanks through it. I was quite happy with the setup until I went to the field to fly the plane for the first time today. The engine turned over, idled, and ran up without issue however when we lifted the plane to test it under throttle, it would die. I understand this means it's running lean, so we richened it, started over again, and got the same results.

Here's what we found....the needle under full throttle was screwing itself back in! Everytime we would open it back up to around 1.75 - 2 turns, it would screw back in to around 1.5 of less under full throttle. I tried bending the indent spring, but this did not work. I could watch the needle turn! The final fix was to put a piece of fuel tubing over the whole needle to add friction. The needle just seems to fit loosely.

Is this a common problem and is there a better fix for this? I love the engine, but it took over 1 hour of head scratching before we found out what was going on. For a while we just thought it was running lean. We now realize that everytime we started it leaned itself down!

Appreciate you input

Steve Seward