I have a BBC, not much done to the engine, just solid lifter, decent Cam. My boat starts up and pressure is 50lbs I think its a low volume oil pump, but drops soon as the oil heats up to 15-20, but then after sitting for a few mins goes back up could the oil pump be bad or could it be bearings? I am going to pull the motor over the Christmas Break. The oil had some water in it but I drained the oil twice to clear it up. I am currently running straight 30 weight.