You're working on the wrong end of the system. Try to get the oil distributor removed and give it a good cleaning, followed by flushing the through-the-block oil line with carburetor cleaner. The oil distributor restricts oil flow to the head until the lower end bearings get at least 15 pounds of pressure. If you're dealing with a tired engine with sloppy lower end clearances, there will be little, if any oil flow to the head, especially at idle. Once the engine speed comes up out on the road and the oil pressure rises, there will be more oil flow to the head.
Jerry
