What About Edelbrock 340 Heads?

Sure you could mill the pistons..... Lots of things you can do to adjust piston height. I was just speaking for general info.

I would not ever run .021 gap....... long term on the street.... or even short term myself. The local track guys go down to .025" minimum at times but not regularly...things wear, pistons rock, clearances change at high loads, gap goes down. Seems to me to be quite a risk for an unknown increase in benefit from the quench/squish gap.

I've never seen any info on benefit vs gap...just numbers above which you probably won't get any benefit. I have never seen this effect characterized, but sure have not seen everything! It would be great if someone had such info and could share it.