I found that info from pre '68 Dave and that's what got me chasing this problem. I put an oil gauge on the head above the side cover originally when I fired the engine up. I had no oil pressure there. Thats why I pinched off the overflow tube to see if that would help, it did not. After the new offset rockers were installed, I have 16lbs of oil pressure at the side of the head and oil just oozes out the rocker holes. I never ran the engine with the valve cover off with the old set of rockers because I did not want oil everywhere on my clean engine. Now with the right rockers it's not a problem. Normally my engine has 35-40 pounds of oil pressure idle cold, and driving it maintains that pressure. A hot idle is about 15lbs at 400rpm.
