There you have it.
A defective cam.
I assume by the pattern that all were tapered in the same direction?
If so, that’s two manufacturing problems.
It would have failed prematurely no matter how it was broken in.
Check the new cam before installing.
Usually anything over about .0025-.0030 taper will start to show the pattern running off the side of the lobe.
Sure, that really makes the lifters whip around, but the contact pattern is narrower...... so it wears out quicker.
Also, it should have the taper staggered.
What this incident tells me is...... there doesn’t appear to be any kind of post-grinding QC process.
