Bottom of lifter worn thru
some recent posts on moparts.org about the same crap. all of them even used cam lube / proper breakin / zddp addatives etc.
apparently some of the cams and lifters being sold are not hardened like they should be :/
lifters are getting pit holes on them where they ride on the cam shaft. spinning ok like they should, worn evenly, but full of pit holes
here's the thread:
http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=7785657&an=0&page=4#Post7785657