I'm building a new 383, forged internals, -31cc dished pistons, 67cc chambers, ... about 8.3:1 compression. The heads are O-ringed, and I'm planning to use some SCE self-sealing copper gaskets http://www.scegaskets.com/products/titan.html

I need to choose a gasket thickness, and I want to choose the ideal (most durable, best sealing) thickness copper gasket. If I'm not trying to raise or lower my compression any, what would be the best with the O-rings? I can choose from ~20, 30, 40, 50, 60 thousandths. Any help would be appreciated.

 

You want to order the gasket that will give you a .040 quench

 

When using o rings and copper gaskets you want the thinnest copper gasket you can get away with so the O ring pushes into the reciever groove.

 

I don't have a receiver groove. But that's okay, right?

 

OK that makes sense. Now, I'm using dished pistons [picture], so does that mean that my quench area is only that little bit at the edge of the piston?

 

Yes, the full dish of your pistons essentially gives you quench only at the flat edge of the piston where it meets the flat portion of the head (essentially on the top half, intake side of the head only) Your piston design will allow only minimal quench.