It sounds like my CMI headers after idle time ,water drains out tailpipe at idle doesn't have enough water volume to fill headers to top of the rise .bump up idle a touch to increase water volume mine goes away .on certain days depending on humidity I can see the condensation line on outside of header

my engine is off

Sounds like dieseling. Self combustion of fuel after shutdown. Not good for the engine.

Idle set too high, carbon build up, are a couple of most common reasons. If engine is warmed up it could be do to overheating.

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I am going to pull off a valve cover start it up for a minute or so take a video of anything moving after shutdown... to be continued...........

Sounds like springs and keepers snapping back in place. Very strange.

Happy Labor Day everyone! Check this out......... I cannot believe this!

So it's got to be related to hydraulic lifters or valvesprings - those are the only non-solid objects in the valvetrain that could potentially move after the crankshaft and camshaft have stopped rotating. My money is on the lifters somehow incrementally bleeding down. But that's just my uneducated guess.

Were the balls in those rockers kept paired up or were they mixed? Seen this before and that was the problem believe it or not.

yes. they were a brand new set I installed. I removed the ones with the roller tip from Compcams. They weren't getting lubricated.. Can't use them with a high volume oil pump.

I ordered a set of compcam lifters and stock rockers

did you measure the plunger depth to roller tip from old filters to the new ones ? that one spring looked like it was close to coil bind