kind of figured more of an effect of another cause... just not bright enough to know what to point the finger at. We had W5 mill that cracked the bodies of 4 Comp Cams roller lifters in 50 passes. Changed pushrods and went another direction on lifters, and it never happened again. Figured it was some weird harmonics deal... not like you ever hear of lifters cracking. At least we got lucky changing parts.