Also check for tweeked rod from coolant being in cylinder. Not saying this is the case but I lightly mill all new heads due to new head stress relieving in the box. In many cases it takes .006 thous to straighten a new head aluminum or cast iron. A high speed head and block mill for good surfaces using CBN for cast iron and PCD for aluminum heads. Surfacing Button materials used are Cubic Boron Nitrate (CBN) and Polycrystalite Diamond (PCD). When using MLS gaskets use a high speed mill ONLY for great surface finishes.

MLR426