Shiming the oil pump pressure relief spring

[pistonbroke]

It sounds like the bottom end may have some wear, has it always had this problem or is it a new thing? I had this happen on 38 Lincoln when I added the old style oil filter. I wasn't aware the there should have been a metering fitting(AKA restrictor) in line. if this has been the norm for a long while I would run 20 50 and see if it helps.One last thing would be to put a temporary mechanical oil pressure gauge on it to verify what your stock gauge is telling you. Tim