John Martin John I have heard the same thing. However 2 things I have found to cause this problem. 1st cams with over .600 lift and not being set up correctly to the head and valve. 2nd Oiling of the rockers either kind, the bushing ones have a slot in the middle for
oil, but the older set like mine I had to put a .030" groove to help the oiling system. The new set I got are T&D. Just have to figure witch set of heads are going to get machined for the setup
Rick Lake