Yes,,,could be , all depends on the valve seat ,push rods ,ect. !!

If the valve hangs up it doesn't need to be at every turn of the cam !!

But hey ,,,that's what i think it is ,,,don't beat me to it !!!

And sorry ,because i know thats not what u want to hear !

I would not run like that anymore until u have it figured out . Faster then u think it gets hung up more ( if this is the problem ) and then u slam it on the piston ,valve break's off and ruins the complete block ?!
I would check it !!
Its not that much work !!!

Are your spark plug wires in good condition? How are they routed? It could be a cross fire between wires. But hey, I don't have a boat..............

Then it would do it all over the RPM range !!

Is this only at idle? Has the engine only been run at idle with only momentary lapses into 3-4K rpm?

Thats what he said !

I had the same thing happen with a 400 sbc. I did'nt break anything but I had a "pop" out of #6 cylinder. The pop at idle and also occurred higher up in the rpm range but was on decelleration after I got on it and let off. I readjusted the valves with the engine running and found more power out of #6 and #8 cylinder. The pop went away.

Its not the valves. I pulled the valve cover on the right side and then remembered Gen V are non adjustable. I am pulling the plugs next. I will keep you guys in the loop-

It was a bad plug on #6. Changed all the plugs just to be sure and its good to go!!! Thanks everyone for all the input. Hopefully if the weather cooperates water test this week- I will take pics and video

Glad to hear it was that simple. I look forward to test results. Scottie have you ever had this boat out? Before you started the rebuild?