could be a bad batch of cams.....sucks for sure. hope you have this problem sorted out. i have heard of the blocks shifting slightly during the casting process. this alone could misalign the lifter bores in the block. I buy my cams custom ground from a local cam grinder, so far so good. i have read on other forums from guys complaing about compcams about lobes failing prematurely. sure is dissapointing putting time and money in a motor only to have it fail repeatedly....good luck and hope your runnin soon