[34fordy]

I don't think I asked the question properly. Overhead valve heads are quite thick and I don't think one would want them to be more than a couple thousands from being perfectly flat at the gasket surface. The Ford factory aluminum heads are thin compared to the O'head valve heads. I wondered if the allowable amount of gap either way could be greater on the Ford heads assuming that there might be a few thousands flex in them, as they are not as thick.