HELP Maybe there is someone that can give me some GOOD advice. I have GM 502's and have a nocking sound in one of my valve covers at higher RPM's. Up to 3400 everything is great above that I start to get noise. I suspect I have a lifter not recharging. I am planning on replacing them but do I need to replace the cam at the same time. I have been told all different things , Thank you

By your description Chances are it's something else, like a valve spring issue or rocker arm.

So, here's the best advice, pull the VC now and start inspecting. Then go further (lifter) if needed.

no..............you need to first find the problem, usually valve train noise is more of a ticking, bottom ends knock

Rod bearing FTW...