3412E Petroleum Engine Caterpillar

Illustration 1	g01023138
Injector Mechanism (1) Rocker arm (2) Adjustment screw (3) Locknut (4) 9U-7227 Injector Height Gauge

To make an adjustment to the unit injectors on cylinders 2, 5, 8, 9, 10, and 11 use the following procedure:

1. Put the No. 1 piston at the top center position on the compression stroke. Refer to Testing and Adjusting, "Finding Top Center Position for No. 1 Piston".

2. Injector height gauge (4) is used in order to obtain a dimension of 78.0 ± 0.2 mm (3.07 ± 0.01 inch). The dimension is measured from the top of the unit injector to the machined ledge of the fuel injector body.

3. Turn unit injector adjustment screw (2) clockwise until the correct height is obtained.

4. Hold the adjustment screw in this position and tighten locknut (3) to a torque of 100 ± 10 N·m (75 ± 7 lb ft).

5. To make an adjustment to the unit injectors on cylinders 1, 3, 4, 6, 7, and 12 remove the timing bolt. Turn the flywheel by 360 degrees in the direction of engine rotation. The direction of engine rotation is counterclockwise, as the engine is viewed from the flywheel end. This will put the number 11 piston at the top center position on the compression stroke.

6. Repeat Steps 3 through 4.

7. Remove the timing bolt from the flywheel after all the unit injector adjustments have been made. Reinstall the valve mechanism covers.