VACUUM PISTON GAP ADJUSTMENT

American Motors

• Remove cover plate from top of air horn
• Adjust piston gap by turning adjusting screw. Correct gap is .040"
• NOTE: turn screw clockwise to make fuel mixture richer. Turn counter-clockwise to lean out fuel mixture

Chrysler Corp

• Remove cover plate and gasket
• Remove rod lifter lock screw and remove step-up piston assembly
• Adjust gap in step-up piston to .035" by turning Allen calibration screw on top of piston
• Record number of turns and direction for readjustment after Vacuum Step-Up Piston Adjustment

VACUUM SETP-UP PISTON ADJUSTMENT

American Motors

• Be sure vacuum piston gap is correctly adjusted
• Back off curb idle adjustment until throttle valves are fully closed
• NOTE: Record number of turns so screw can be reset to original position
• Turn idle screw IN until it just touches stop. Then turn IN one full turn further
• Depress vacuum piston fully while holding moderate pressure on rod lifter tab
• Tighten rod lifter lock screw
• Release piston and rod lifter