"""My first flight I had to screw the needle out some to obtain 9,200rpm after
take off it went dead rich.
Rpm was checked again on the next flight with same result.
This had me a little confused removing a head shim had made the motor run
rich?"""
HI Paul
Several other things could happened here, however the motor could have gone rich because you turned the needle out and made the engine richer.
When adding or taking away a head shim, many times you *cannot* set the engine with a tach to the same RPMs. The motor is now setup differantly and will need a differant setting.
It sounds as if the motor was a little richer at the ground launch , then when it unloaded in the air again went richer. try the same setup with the gasket removed but set the engine to *sound the same*, that is sound like the same setting you had to start with.
Also compressing that engine on most setting will make the engine run in a stronger 4 cycle with much less breaks, and decompressing will make the engine run in much more of a 4-2 break. That is it will break earlier and more often with the less cpmpression.
You also would benefit from using a .003 or .005 shim differance, rather than using .008 , that sometimes, is a pretty coarse adjustment on a st 46.
The last comment is if the ABC piston sleeve set is not completly broken in it could have very easily heated up on the ground from the extra compression, this would require a richer needle setting on the ground, which would have gone even richer as it went up in flight , unloaded ,and cooled down
Regards
Randy