What is your oil pressure at hot idle?
Noises in the valve cover (s) can be, but are not restricted to; collapsed lifter(s), bent push rod(s), rocker(s) that are loose/worn/broken. broken valve spring(s) or bent push rod(s). Then there is the possibility of a bad cam lobe(s).
Merry freakin Xmas......
Chicks dig me.....Fish fear me
Getting older, I have developed some special skills. I have the ability to cough, sneeze, fart and pee at the same time.
"If we cannot afford to take care of Veterans, then we should stop making them."
David C. Wilker Jr. USAF (RET)