16. We’re running a Melling high volume oil pump propelled by an ARP pump shaft. Always disassemble your new pump for a blueprint check. Check rotor end clearances and pressure relief valve for freedom of movement and spring pressure. Take note of rotor indexing before disassembly. When complete, fill the cavity with engine assembly lube or SAE 30-weight engine oil. During installation, check clearances between the pump and the crank counterweights. You need at least .060-inch. Never remove metal from the crank.