Whilst trying to solve a wet-sumping problem, I have found a different oil-related 'discrepancy.'
This is a picture of the r/h end of the front crankshaft, with the cap removed. The engine has a Mk1 bottom end with a Mk2 top end fitted by the previous owner. He has made many other modifications and I think that I have just discovered one more...
Another member (thanks, Gui) provided me with a picture of where the oil pressure relief valve is (should be?) located on a Mk1 Square Four. It is clear that mine does not have one!
The oil pump is a Morgo without a built-in oprv, so it looks like there isn't one anywhere on the engine.
I'm waiting for some fittings to arrive so that I can connect an oil pressure gauge so I can see what is happening, but in the meantime, would anyone have any comments on this puzzling situation? Could it be that the previous owner fitted a front crankshaft from a Mk2? Is there any way to retro-fit an oprv, without having to strip the engine?