Adjusting CUCV Injector Pump

[MarcusOReallyus]

You have to rotate the engine untill the screw lines up with the hole.


Turning adjusting screw clockwise will advance and counter clockwise will retard fuel.

The screw in question has nothing to do with the function of the pumps advance mechanism. This screw simply retians a torsion plate that holds the rotor roller shoes onto the rotor. The rollers spin around the cam ring (thing with hole in it you are looking through) and get pushed in/out buy the lobes on the cam ring. As these rollers, that are attached to shoes, that are held in place by a torsion plate, that is secured to the rotor body by the secret screw, move in/out, they act on pumping plungers internal to the rotor. The secret screw, by adjusting tension on the torsion plate, adjusts the roller to roller distance, which also adjusts the size of main fuel cavity between the pumping plungers.

- Turning the screw adjusts the size of the main fuel cavity, allowing more/less fuel per stroke, that’s it....

Advance mechanism operates by a pressure differential between the transfer pump and cavity pressures. The cam ring is attached to a pin, that is attached to a piston, that has transfer pump pressure on one side, and cavity pressure on the other. This piston slides back/forth in the little perpendicular cylinder on the bottom of the pump. When the piston moves one way it moves a pin, the pin moves the cam ring, this advances or retards the injection pump timing.

- Pinch the return fuel hose coming out of the top of the pump while at idle and normal op-temp. What happens? The engine should die. This is because by pinching the return fuel hose, you have just spiked the pump cavity pressure, sending the pump into full retard. The engine should stall if everything is working correctly.


Best results for power I have seen are a combination of plunger increase (turn secret screw) and an increase of a few hundred RPM. I would do this by adjusting mini-max governor spring tension with a shim pack (washers). This is easy to do on the dyno or in the field. Have not messed with delivery valve size or x-fer pump pressure increasing power but bet a few ponies are their as well.