Ticking during rev-down?

[Fred 86 GN]

I have noticed a loud "ticking" noise coming from the upper passenger-side of the engine that only occurs when the engine revs down to idle from being revved up. Rev the engine up to 2000rpm or so, then release the throttle and as it returns to idle speed I hear "tick tick tick tick tick..." until it reaches idle speed then it goes away.

What could cause this "ticking" noise?

My guesses -- PCV valve cycling, something not right in the valve train....

Sounds too metallic to be an exhaust leak, but could it be?

Thanks,

 

[pracingrev1140]

check your spark plug s i had one loose on the drivers side turns out i was hearing compression leak .RR