How much oil is visible under the Valve Cover with engine running?

I noticed when I took off the oil cap and looked thru the oil fill hole, the only oil visible is on top of the rockers. Im not sure how much or little should be flowing thru there with the engine idling. Anyone know?

Psi cold= 65psi
Psi hot=20psi

I have a coming and going single lifter tap every once in a while, And when I added seafoam, as soon as it hit the "bottom" my lifter tapping stopped. (It still comes and goes, just thought it was odd)

You won't have a whole bunch flying around in there. You might have a sticky lifter.

How loud is it? Can you hear it while driving? With the hood close but standing next to it? Or only with the hood opened? Are you sure it's a lifter?

It may take a while longer or even another seafoam treatment.

So what Im seeing is ok....good.

I can hear the lifter tap come and go in the cab, outside, with the hood up or down, and when I put my ear right up to the valve cover, its right under there. Ill see what the seafoam does...

Thanks for the help.