408 valve train noise

I don't know about the lifters collapsing at RPM thing, but my Magnum is noisy at idle. Had the same thing on hydraulic roller fords with aggressive camshafts. The grinders say the lobes on the cam just make them noisy.

My lifters bleed down very fast too. Its annoying but it hasn't hurt anything so far. I haven't checked my lifter bores for partial chamfering....WTF Mopar? They did that on Magnum blocks?

Also, that seems like a lot of lift for the R/T heads. Have you checked your clearances on retainer/guide and coil bind?

Good luck

Steve