Valve clatter/normal noise

With several cars in my collection I observe that the engines are different in noise. Today I had a very quiet 420G running next to another G where the noise is noticeably higher (it happens to be the car with a very efficient flex fan, which gets much noisier on accelleration, but this was at tickover).
My question is, how much of a noisy engine is due to valve clearance, and what else plays into the equation? I refer to cyl head noise only.

Listen to it with a mechanic’s stethoscope or a long screwdriver in the ear. You can usually identify where the noise is loudest. Valve clearance is the most common problem, followed by chain tension.

The equation gets complex: not just valve lash, but tappet sloppiness in its sleeve, and possible bearing wear, plus a possibility of the distinctive ‘double clatter’ of a too-short valve stem.

Thanks. Chain tension is perfect in all my engines. I have and use a stetoscope. I thought that valve clearance did not change over time…!?
(in a semi race 120, I have racing cams and that engine makes a lot of noise and sounds very different. Sigma in England built it. A very cool car.

Wasn’t engine noise an issue with early 4.2L engines? Something to do with crankshaft resonance? I feel like this has been discussed before. Does one of them have later parabolic cams?