I've got a set of .030 over 307 forged pistons that I will be using in a 250. The domes on the pistons are quite big......how much material can I safely remove, or what is the minimun thickness of a piston top I am allowed? I want a hot street motor , but still able to use pump gas.

Make sure you stay around .150 thick, you can go a little thinner, but you need to make sure your tune-up is real close. If they have been balanced before, make sure they didn't drill on the underside of the domes, if so you need to be .150 at the bottom of a drilled hole and not on the flat surface underneath. Deburr around the topside afterward also.

Just a suggestion,,,get your deck height close to zero,,,,,,that will help with not getting detonation on pump gas.
(This step alone will help tremendiously!)

I have 0 - +.003 positve deck height,I ran 12:1 compression & had 220 PSI cranking compression on pump gas & did not detonate.


MBHD