Comp sent me a 1722/1850 grind. The problem is that with the 1.70 rockers the valve accelerates faster than the piston down the hole. So I have lots of VP clearance at TDC but the valve catches up to the piston at about 10 degrees ATDC. If I dial the cam in at 4 degrees advanced the valve kisses the piston on the way down. If I put it in straight up I might have 0.035 clearance. If I retard the cam a bit then I have clearance.

I also have a Scott Brown cam which is a little smaller than the Comp and I have a Crower 300R which is another 10 degrees smaller yet. The SB cam also smacks the piston. I haven't tried the Crower yet.