Sounds familiar. Pre-38 timing cases have the oil drain holes much higher than later engines. This is my 37 inner timing cover:
IMG_20260331_135512.jpg
There are also correspondingly higher drain holes in the crankcase. Do you have the higher drain holes? Later covers have just one drain hole much ...

Yes, the unthreaded hole is the one I mean. I have a prewar bike where the hole is at a much higher level. Oil should come out from there. In the case with the cam you have a certain oil level, and that flows through this hole into the outer case until that oil level is reached in the outer case ...

I am not quite sure which hole you mean. Is it a hole left to the oil pump, and you can see it with the oil pump fitted? Then that will be a hole that connects the outer with the inner timing case. It should be open.

Now it sounds more as if the problem were the supply side. If the sludge trap was ...

Terry, I am sorry. You can confirm your suspicion by blowing into the pickup pipe and blocking the copper pipe at the other end where it comes out of the crankcase. If you detect a leak there, I cannot think of another solution than to split the crankcase.

Just to exclude a simple problem: You said that the plunger in the oil pump creates a vacuum when you pull it out. But that doesn't rule out that something is wrong with the ball valve in the pump. Paul has described the test procedure above.

If you remove the outer timing cover and find a leak ...

Terry, I think you said that you directly poured some oil into the crankcase, but have no oil return? If so, your problems have nothing to do with the sludge trap. The worst case scenario is that the oil pick up tube in the crankcase has come loose. I think the next step is to remove the sump plate ...

Nev, maybe I give it a try and fit the timing cover without gasket next time. As I said, I tend to follow blindly what Waller says. I realize we may have better sealants today.

Nev, Waller writes: " Any air leak between the timing cover and crankcase, at the point where the short copper oil-return pipe extends, must be prevented by fitting one or two 0.005-in. small circular paper washers [...]" I have never dared to question Waller's advice and I have never omitted the ...

After removing the sump plate, you can also attach a piece of clear plastic tube to the copper pipe in the crankcase and put the other end in some oil. Then you will see quickly whether it sucks up oil when you rotate the engine. But if the small washer is missing, I would take off the timing case ...

I think the decompressor sits on the inside of the rockerbox where its hard to reach (not on the outside of the engine plate). Right? The only adjustment I can think of is the position of the lever on the spindle of the valve lifer. This lever is a taper fit on the spindle. You can unscrew the lock ...