blkvzss

Just trying to find out what head gasket size are people using on a 3.908 bore on a Ls1. Is a 3.910 cometic gasket cutting it a bit to close or ok.

JakeFusion

iTrader: (7)

What heads? You pick gasket based on the biggest bore size, whether it is engine or head.

The 3.910" Cometic should work if the engine is the bigger of the two bores. You just don't want any gasket material hanging out in the fire path.

blkvzss

Heads likely be PRC 215s and piston will be .010 out of the bore so I was worried a 3.910 gasket size would be to tight with a 3.908 piston size.

Burken01

iTrader: (88)

You go .0020-.0030 over the cylinder bore in your case for gasket size..

3.910 is perfect, it is .0020 over 3.908

Plus if the bore is 3.908 right now, then the piston is @ 3.904 (assuming an NA build), which means you will be fine!!

And since you know the piston is .010 out of the hole I would get a .045-.050 thickness gasket and have an optimal quench of .035-.040

Goodluck