Valve train noise lead to oil pump change. with new pump pre-oiled with drill technique, oil pressure builds to 15 psi., installed distributor and started eng to find no oil pressure on direct reading gage. measured all dimensions of distributor to pump shaft, all perfect. only differance is with eng. running vs drill pre-oil is rotating assy moving, any ideas as to why the differance and what damage can I expect? Thanks in advance.