One other thing to check. I supply the VC with 7/8" long bolts. I have found on some heads that the bolts will bottom out in the hole before tightening the VC down. If that is the case, get some 3/4" length bolts.
Scott is correct, the gasket sealing area on many of these heads is as cast and not machined flat. On the worst heads, 2 gaskets will allow them to seal.
