shows how much oil to the rockers at 2000 rpm with the valve cover off. I get 30psi oil pressure at idle, mid-range and at 3000.
If you idle it though, the volume out of the rockers is very different. It more seeps out than runs out. Very little oil coming out at all really. It sounds to me like you do not have a problem other than the engine may be slightly worn.
Pull the distributor and run a drill with large screwdriver chucked in it to be sure without running the engine, to see if passages are clear. Agree with trying another gauge too.
