Issues with roller cam

[JMD]

I installed a Howard’s brand roller cam as well as a set of their lifters in my Gen IV 454. Put about 1500 miles on it when I began to hear a knocking noise from the valve train accompanied by a noticeable drop in power. Figured a lifter had collapsed, but it had actually worn down the #6 exhaust lobe to basically nothing. I’m thinking that the knocking noise I heard was the cam beginning to chew up the lifter casing...

Looks like the retainer that keeps the lifters in line broke off which allowed the roller to rotate 90* on the cam. Any idea what could cause this other than a faulty part? You can see the broken stud laying on the right side of the lifter valley in the second picture.

At this point I’m looking at a complete engine rebuild, there is a TON of glittery stuff in the oil, and almost every cam lobe has been damaged.