I have a 69 Camaro with a 1974 396 with peanut truck 454 oval heads. I bought the car 2 years from Volo auto museum so I don't have background information. I drive the car about 10 a year for about 150 miles total. I was on the interstate and developed a valve tap going about 60-70 all the sudden. I found cylinder 2 exhaust valve fairly loose (standard steel rockers and hydraulic lifters. The gap between rocker and lifter was about .008". I adjusted the valve and tap was still there. I flushed for 6 min with mystery oil and changed oil. still tap. I installed new lifters. Still have tap but with new lifters the tap is much lower. Not sure what to do to try. I did a compression test and the results were 140 145 123 130 132 115 139 122. Six cyl was suspect so I reset the valves again and still have a tap. The tap is not a idle comes in around 1,500 RPM. Any help would be great. I can do some things and know some things about motors but not an expert my no means.

Jack

 

Did you flush out, or put the push rods in a solvent vat? Could be one is partial plugged, although thinking if that was the case higher rpm would increase higher oil pressure. Recheck your rocker arms, just a suggestion. I had years ago a cutout valve cover that I would install to actually take the mechanical slack out with it running.

 

Thank you for the interest in my problem. I did spray carb cleaner down the pushrods when they were out. I did some more investigating and took the header gasket off of the side that was making the noise. I found the gasket material broken away from the metal inter support. in two cylinders in the same location. I ordered some .125 thick gaskets from Mr. Gasket. There coming today and hopefully this will solve the problem
Jack

 

when i install headers i get some of those thick aluminum header gaskets. this way if a bolt ever backs out all i have to do is re-tighten it and not replace the whole gasket because it blew out
kind of looks like these
https://shop.advanceautoparts.com/p/...E&gclsrc=aw.ds

 

Valve tapping can be an exhaust leak like Irish-Alley posted.