Originally posted by Motorman
on a 12 engine I would only advise going .004 thousanths over or under .018. so that is .014 or .021. I have run as low as .008 but this was with tremendously increased exhaust timing and to regain static compression ratio. to little and the piston can hit the head as you have to take into account rod and piston growth relative to their tempratures.
On my P/S sets I am able to run engine from .125mm (.005) to .15 mm (0.006) shims and with 20% or less fuel with dramatic power increase overall, temperatrure will stays within 210-220 and no any detonation was seen so far ( ones by my mistake was hell of detonation in Texas, but there was my mistake with tuning). The engines has defenetly different timing setting from stock version, but I have never faced piston hit the botton.