Oil pressure relief valve maybe?

[gentilepiano]

I have a Series III 5 main bearing engine. I am still trying to hunt down a intermittent clicking sound.
The engine starts easy, runs smooth, plenty of power etc. A clacking sound is always present. At an idle it will clack several times then a pause and reoccur every count to 14 or so. The interval between the clack increases with rpm. I have adjusted the valves, disconnected the fan belt, but the sound is still there. The clack is not loud, but ever present.
My thought is that maybe the oil pressure relief spring is broken and the sound happens when the the oil pressure builds and then bypasses. I have had mechanics look and listen, but no one has an answer. The clack sounds like a loose ball bearing in the cooling system. I have probed around with a stethoscope, but the sound as to it's exact location, is elusive.
Any thoughts ??
Thanks for your consideration!

[SafeAirOne]

Have you had a peek at the timing chain and tensioner? I believe they can cause the symptoms you describe if they're slack/worn (others can confirm--I don't have a timing chain).

At least that's the advice given last time someone reported those same sounds here on this board, IIRC. Might search "timing chain" or something similar for the thread.