I agree with 4onthefloor. Not too little, not to much oil for the rockers.
The auxiliary oil line to the head was installed when engines with early blocks got a 58-62 head and rocker assembly replacement.
The later rocker arm oil passages and pipes were altered to match the difference in oil pressure to the head from the later blocks. The supply pipe to the rockers were kinked on purpose.
Early or late heads are identical with oil passages, but watch for the later rocker arms with cast#s 85,86,87,88 and kinked pipe.
If you got earlier rockers with different cast# you don't need the auxiliary line, as they allow more oil flow.
Later blocks should always run matched later rocker assemblies or you probably get too much oil up there.
It's just a valve cover without torque-ing down, mostly to keep debris and dust out. Rockers shouldn't splash and spill or worse flood valve guides.
If you got a vented valve cover or PCV valve that leaks oil - check your rocker cast#s - could make a difference.
