Originally posted by aptar
Another possibility is, if the engine has a head shim, remove the head shim for a small increase in compression ratio.
This is a good idea for low nitro fuels...10% and less. If you are using more than 20% nitro you might want to add a head shim to lower compression and prevent detonation...which will slow the engine down.
GREAT tip on the slightly rich needle setting! The hotter an ABC engine gets while running the looser the piston/sleeve fit gets...and the less power it is able to produce. I usually point a plane straight up on the ground and tweek the needle just slightly richer than full lean...end of tank runs are excellent!