Lots of good info, thanks. The cam I have is the Lunati Voodoo with .454/.475 lift, 213/220 duration @ .050, 112* separation. I'm not home and don't have my cam card with me, and I don't know what the lifter profile is. How do I check the lobe taper? I'm guessing with a precision straight edge and feelers? I misspoke earlier about the lifters, they're the matching Lunati lifters that came with the cam/lifter kit, not Comp Cam lifters.
And I've always used the same Lucas high zinc with a Wix filter, nothing else.
For some reason the lifter has mushroomed at the lobe end, maybe it got so hot after failing that the metal expanded to the point where it couldn't raise into the bore and got smashed harder and harder into the cam?
