Quote:
Originally Posted by nkaminar
The bring a seat back to the correct width, cut the seat to 45 degrees. Then cut the bottom of the seat to 60 degrees and the top to 30. As you are cutting, check to make sure the width of the seat that is at 45 degrees is in the center of the valve face. Do a light lapping of the valve to the seat. Just to the point of having a uniform grey ring on the valve. Some mechanics will cut the seat to 46 degrees which provides a sharp edge at the top of the valve face and, it is thought, a better seal.
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Good info to give to my machinist. I always lap valves just enough to leave a grey ring on the valve face. An old timer told me once to take a lead pencil and mark the seat with it, if the valve removes the mark when you rotate the valve, the seal is good.