Best explanation I've seen so far for Hemi cam/lifter failures

408 swinger said

I was under the impression that the 6.4 stuff didn't fail either. Lately, I've seen some for sale with bad cams. On that note, those seem to be MDS engines. They don't say which lifters had failed, though. In a previous thread about this, I had posted a pic of an Eagle 5.7 cam lobe. That lobe was a non-mds lobe. I'm starting to think that maybe with my "bad metal" theroy, combined with Uncle Tony's theroy, could maybe explain?

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I dunno much honestly, only what I'm told/shown. I tend to believe it's a combination of low rpm operation (idling) and either crap cams in the 5.7's and MDS in 6.1 and above. What I CAN say, is I have a 6.1 and a 6.4 in my garage. The 6.1 mileage us unknown and the 6.4 is a 2018 with 18k on it. Both have spun rod bearings. I haven't torn into the 6.4 it to check the lifters yet but at this point it would be impossible for me to determine which happened first if there's a failed lifter/lobe.