Hey Guys,
I'm building a 427 BB and I'll be using a GM TRW 12.5:1 piston. The number stamped on the piston is:

GM 3959108 Domed, Intake valve reliefs are OK. The exhaust doesn't seem to have any?

I'll be using a Lunati Solid roller(custom grind 266/272 678/688 110 LSA), so has anyone used these pistons or does anyone have any more info on Piston to valve clearance issues?? I wouldn't mind getting the compression down to 11:1,so fly cutting them will be OK.

Ant info would be greatly appreciated! Thanks

P.S. The heads will be AFR 305's with the CNC 121CC chambers.

Same as L2308's. You need to have some one check the clearance no matter what. I tried to avoid this too but my friend done it for me. Bigblocks will smack the exhaust valve 1st if too close. Better pay someone a litle now than a motor later!! Also 11:1 requires just as good of grade gas as 12's so why leave the TQ & HP on the table? :rolleyes: :rolleyes:

those chambers might knock it down to just under 12, which, agree with above.