V6camaroman

Hey there guys, been around on the forums for a longg time now and im working on another 305 motor for my new 86 z28 that I have. Ive got a few questions about which headgasket to use on my 305 build that im doing. Looking for some technical data, as most of the 305 gaskets ive found dont list a bore diameter or compressed thickness in their descriptions?

The only 305 application headgasket ive found with the data I need is the mr.gasket one #5780G which is a .028 compressed thickness with a 3.87 bore diameter. My problem is most of the performance (thin) headgaskets ive found are all a 4.1xx bore which I know is too big. I have the block decked so the piston is .012 in the hole and the heads are milled to a 52cc. Im trying to keep quench tight on the motor, thats why im concerned on the gaskets. Has anyone used the felpro #8510PT? What is the diameter and thickness of that gasket? What do you recomend?

five7kid

iTrader: (14)

If the pistons are .012" down in the hole, the .028" compressed gasket would be perfect.

V6camaroman

Im sorry I actually just re-read what I wrote and realized I mis-typed it. I was at work and in a hurry when I wrote this up. My piston is .010 in the hole. And I also did a little more reading on the #8510PT felpro gasket, its looking like those are .039 compressed thickness. They are aso more readily available. Which should I go with? Was hoping some of the old 305 guru's (mw66nova, FAST355) would chime in....

mw66nova

iTrader: (13)

the last gaskets i used before going lsx was a steel shim head gasket. had a 4.1" bore if i remember correctly. it was like .016" maybe. if you can find a .028" gasket i'd imagine you'd be OK even if the bore is a little big. the motor is actually still together with no signs of detonation, even at 10.5:1 with iron heads and 40* locked out timing. run 93 octane and it should be a-ok