my 468 motor has less than 3000 mi.
and i'm getting a intermitting noise under valve cover on pass side sounds like loose rocker but it comes and go's when i pulled the cover all is well???

A couple of things to check are a worn rocker arm and/or worn valve tips. I've also heard a loose guide can make an erratic ticking noise. A worn or damaged lifter would do the same thing.

Jody