GM LS-Series Double-Roller Chain Oil Pump Spacer
Warning If you are using a spacer to reposition the oil pump forward in a Chevy LS engine so that a double-roller chain can be installed to drive the camshaft, use caution to make sure the pump has sufficient end play and is not binding. If the pump binds, it can wear the thrust surface inside the pump and damage the housing and drive gear. The accompanying photos show the result of what happens when the oil pump lacks sufficient clearance because of a stack up of manufacturing tolerances when a spacer is used. The thrust surface of the housing and the inner drive gear both have turned black from the excessive friction and heat. Steel turns black at 800 to 900 degrees F, and blue at 1,050 to 1,100 degrees F. The thrust surface in the pump housing has also been worn down nearly .014 ̋. To reduce the risk of oil pump binding, assemble the crankshaft in the engine block with the pump and cover bolted down, but with no pistons or rods or upper valve train components installed into the engine yet. If the crank rotates freely, the pump should have sufficient clearance. But if the crankshaft does not turn freely, the oil pump is probably binding.
Vern Schumann
Schumann Sales & Service
Blue Grass, IA
September, 2015
