Whether you are reusing the stock Twin Cam oil pump or upgrading the oil pump, it is very important to thoroughly clean, identify, and inspect all Twin Cam oil pump pieces before assembling the unit and installing it into the bottom end of the motor.
The Twin Cam oil pump is a relatively simple assembly that performs the complex job of creating specific vacuum pressure and inevitability, oil flow. The Twin Cam oil pump consists of a housing that contains two gerotor gear sets. One set of gears are oil feed, the other set is used to scavenge the oil. The feed gears distribute oil to the engine. The scavenge gears draw oil from the cam and flywheel compartments and returns the oil to the oil pan.
Each gerotor gear set has one inner and one outer gear. The inner and outer gerotors have fixed centers that are slightly offset to one another and the inner gerotor gear has one less tooth. As the crankshaft rotates, the cavity between the inner and outer gerotors on the inlet side of the pump increases in volume. This movement creates a vacuum that causes oil to be drawn in. The cavity continues to increase until the volume is equivalent to that of the missing tooth on the inner gerotor. The inlet and outlet sides of the pump are sealed by the tips and lobes of the inner and outer gerotors.
Continued rotation moves the pocket of oil to the outlet side of the pump. In this area, the cavity decreases in volume causing the oil to be pushed out the discharge port. As the cavity on the outlet side is emptied, the tips and lobes of the gerotors create a second seal and prevents oil on the outlet/high pressure side from being transferred to the inlet/low pressure side. When moving continuously in conjunction with one another, the gerotors provide a continuous, steady flow of oil.
Next, Mike will be prepping to install the Twin Cam oil pump and the cams, with support plate.