One of the inevitable consequences of inadequate oil flow to stovebolt rocker arms is worn rocker shafts. For some reason, the rocker arms themselves don't seem to wear as badly as the shafts they're mounted on. Intermittently, new replicas of stovebolt rocker shafts are available on Ebay, but the supply is far from steady, and the prices are fairly high at times.
Here's an intererting factoid- - - -only the bottom of the shaft wears, due to the upward thrust of the pushrods, and also the tension of the valve springs. "Simple solution- - - -just turn the shafts upside down, and let the rockers run on the unworn part". Not so fast- - - - -there are oil holes in the shafts that need to point down- - - -turn them up, and the rockers don't get oiled properly. However, here's a sneaky trick- - - - -use a solid carbide drill bit, a V block, and a drill press, and drill the oil holes all the way through the shaft. Then thread the top holes, and use brass Allen set screws to plug them. With a litle creative file work it's possible to use the brass plug to stabilize the rocker, letting the plugs stand a little proud of the worn areas. Be sure to find and fix the cause of the restricted oil flow to the cylinder head while you've got things apart.
No, it's not a perfect fix, but the above procdeure can be employed to salvage a set of rocker shafts that might otherwie have to be scrapped.
Jerry
