Hi, I am trying to lap a 12L14 valve into a cast bronze seat. The valve is 5/16 inch in diameter, and both the valve and the seat are cut at a 45 degree angle. I am spinning the valve with an electric drill, varying the speed and using an 800 grit lapping compound. The valve has seated very uniformly, but the finish is unexpected. There are fine radial grooves that I can see and feel with my fingernail on both the valve and the seat. I thought it would be more of a uniform finish. Nothing I do seems to get the grooves out. What am I doing wrong? Thanks, John.