ADJUSTMENTS
The accelerator pump has two adjustments. The piston-to-shaft pin position is set at the factory. Capacity adjustment should be made only if operating arm is replaced.PIN POSITION CHECK
- Remove upper body of carb. Turn upper body assembly upside-down
- Disconnect pump from operating arm
- Disassemble spring and nylon keeper that retains adjustment pin
- Check pin position. Refer to specs. If pin is not in correct hole, remove pin and place in specified position
- Reassemble nylon retainer, spring, and spring retainer. Reinstall upper body
CAPACITY ADJUSTMENT (AFTER PUMP ARM REPLACEMENT)
- NOTE: Throttle plates, shafts and lever must be installed to spec to properly adjust new pump arm
- Remoe mechanical fuel bowl vent rod and bracket assembly
- Remove two expansion plugs (1 barss, 1 aluminum) from air horn over pump arm. This gives access to adjusting screw and pin hole
- NOTE: penetrate plugs with sharp punch and pry out
- Remove carburetor upper body
- Remove vacuum piston limiter lever and nylon pump arm from pump lever and shaft assembly
- Remove pump adjusting screw (5/64" allen wrench) from original nylon pump arm
- Install adjusting screw in new pump arm. Position so that one full thread of the point end of screw shows below pump arm
- Install nylon pump lever and shaft assembly with "E" clip
- Mount upper body to main body
- Install pump rod into correct hole in throttle pump lever
- Position pump gauge pin through pump gauge access hole so pin rests on top of pump stem and shown in above image
- Place throttle lever at idle position
- Measure from top of gauge pin to upper body casting surface. Record measurement
- Move throttle to wide open position. Measure distance between top of gauge pin and upper body casting surface again
- Difference between two measurements should be 5/16" (.312")
- If not, adjust by turning pump adjustment screw CLOCKWISE to INCREASE or COUNTER-CLOCKWISE to DECREASE reading
- Recheck reading after adjustment
- Install new access hole plugs
- Install mechanical bowl vent rod, bracket and screw
- NOTE: Do not try to adjust accelerator pump with nylon nut or vacuum piston limiter lever
