360 Magnum valve train noise

junkyardhero said
the inherent design of the lifter causes this to some degree.

but, it may be something else entirely. you didn't give us any other specs, so i'll paint with a broad brush:

wrong oil viscosity. worn lifters-- mileage/age, push rods too short for cam, thick head gaskets, detonation, valves sunk into heads... or, an exhaust leak.

Also add **** in the check valves of the lifters to your list. 95% of the time when a hydraulic makes noise AND is adjusted correctly (proper preload) the check valve has trash in it. Steve Brule told me once “hydraulic lifters are like tiny little oil filters, they catch everything “.