I feel better already...the bottom end is getting oil.
It does take a minute or two for oil to get up into the rocker shaft and work it's way out through the small rocker arm passageways. You can run the engine for a while if you have poured some oil over the rocker arms.
The rocker shaft oil has a long trip to take and everything along the way must be right for the oil to come out the rocker arm tips. Let's review the oil's pathway.
The first "turn-off" for the oil is at the rear cam bearing, this has to be installed correctly so both holes in the rear bearing line-up to the block passages. The bearing can be installed backwards or not aligned properly to the block holes.
The oil is then metered through a small cross hole in the rear camshaft journal. I have seen some cams missing this hole or they had the cross hole plugged with crap. (spun bearing material, sluge, carbon etc.)
The oil then travels up a long drilled passageway in the block and has to get by the head gasket and into the head. I have seen poor gasket alignment at the head cause oil flow problems.
There is a short passage from the head gasket surface into the lower rear head bolt bore, then from the head bolt bore, up to the rear rocker shaft tower retaining bolt's tapped hole. If you have concerns about these intersections, remove the rocker shaft and the lower rear head bolt and "fish" a wire through these holes to be sure they are clear. Note that 'fat' head studs or rocker shaft shims can "choke-off" oil flow up into the shaft at these locations.
OK, we now have oil getting to the rocker shaft, there has to be enough volume to fill the shaft so oil can be forced into the rocker arm passages. Any cracked rocker shaft towers, leaks around the mounting bolts or the shaft's end plugs can bleed-off pressure, preventing oil flow into the arms. Shaft mounting bolts that "bind tight" before drawing the shaft down solid to the tower saddle is a problem I have seen.
A common cause of no oil flow into the rocker arms is an incorrectly installed rocker shaft. Pre 1980 shafts can go on one of 4 ways, only one way allows oil to pass into the rocker arms. There is a small flat on the end of the shaft that must be forward and up. It this better to just be sure the shaft's oil feed holes are low and pointed towards the manifold ports, about at the 4:00 position when looking at the front of the shaft.
The most common problem is that the small rocker arm oil feed passages get plugged-up. If a dirty rocker assemble is "hot tanked", the small passageways get completly plugged-up. (!?!) You can quickly test each rocker arm oil passageway by using a can of carb. cleaner with a extension tube. (the red plastic tube that plugs into the nozzle) Stick the tube into the arm's top oil feed hole and give it a squirt, cleaner should spray-out the arm's tip hole. This can be done with everything mounted in place.
That about covers it.
DD
