I had a high volume pump on. I thought I might not have enough oil. of cource I know the way I added oil to the system would not help in any way other than cool the oil. But the first time I started it I just had the factory filter on. I had 40 psi then went to 5. Pulled the engine checked the cam bearings and sure enough I had a gap behind the rear cam bearing and the plate in the block. Fix that put a stock oil pump on. Started it and had 40 psi oil pressure then went to 5. When I primed the engine I had plenty of oil flow out of all the rockers.