Originally posted by terry sturchio
I wouldn't take the head shims out with 30% fuel. Most engines are shimmed for 20% average conditions. Usually you want to add shim to an engine to run 30% as the compression will increase, causing a risk of detonation. You won't have a problem with this during break-in cause the over-rich mixture will keep the plug cooler, but when you run in warmer weather with the engine leaner for race-tune, detonation is almost inevitable without any head shims. At least put the same shims back. Some guys remove them during break-in to compensate for the over rich mixture. The extra compression helps force the engine to idle better when super-rich. Keeping that sucker running is the hardest part of break-in. In some engines, running no shim can actually cause the piston and plug to contact each other.
I agree, and
The best part of wakin up.....is NITRO in your cup!
I agree again...