I am referring to the machined portion of the top of the cylinder head. What are the tolerances?
Is the surface finish just a milled surface? Ground? Ground and sanded? Sanded and lapped with polishing compound? Or do they rely on a gasket material to fill in the micro scratches from milling.
And the most critical part of this question, what are the tolerances for flatness of the surface? Is it loose as a goose like .005"? .002"? Or are we talking in the sub .001" range? If one had a cylinder head out on a bench and was checking for flatness, where would they want to measure from?