Vacuum Piston Gap Adjustment

Fig. 7 Vacuum piston gap adjustment:

Fig. 8 Vacuum piston adjustment:

1. Adjust vacuum piston gap to specifications. Rotate Allen head screws on topof piston to adjust gap, Fig. 7.
2. Install vacuum piston assembly into air horn bore, ensuring metering rodsare positioned in the metering jets.
3. Back off curb idle screw until throttle valves are completely closed. Countnumber of turns so that screw can be returned to its original setting.
4. Fully depress piston and while applying moderate pressure on rod lifter,tighten rod lifter screw, Fig. 9.
5. Release piston and rod lifter and reset curb idle screw.