Originally Posted by engineczar
Which heads are you using? What intake gasket are you using? Also when you assemble it how much gap do you have between the end rails of the block and the intake?
Heads are ProFiler 195's ported to 203, 64cc chambers, angle plugs. Intake is LT1/Z28 dual plane, ported. Using FelPro 1205, which is trimmed to port size. This leaves narrow sealing areas in the gasket and the intake, which was not designed for the larger ports in the head. V E R Y careful alignment required, and it's possible that some areas may be "marginally" sealing due to some areas around ports which are as narrow as 3/16". Very hard for me to determine by eye, so that's why the request for a possible pressure test that can be done.
Block was decked so pistons are .004 above decks (ie: about .030" removed). Have about 1/32" thickness RTV on front/rear block walls, I believe. I did have to elongate manifold bolt holes downward towards valley in order to get bolts threaded into heads. Ports in LT1 are slightly smaller than ports in heads, so manifold ports are completely "within" head ports