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Carburetor (4.2L) R & I: Reassembly

  1. Install idle mixture screws and springs in body. Tapered portion must be straight and smooth. If tapered portion is grooved or ridged, use a new screw. DO NOT  use a screwdriver for installation.
  2. Turn screws lightly against their seats with fingers. Back off number of turns recorded at disassembly. Invert main body. Place gasket and throttle body on main body and align. Install screws and tighten securely. Install accelerator pump ball, accelerator pump and spring assembly.
  3. Install accelerator pump discharge check valve ball in discharge passage. Pour clean unleaded gasoline into carburetor bowl approximately 1/2" deep. Insert pump plunger into pump cylinder. Operate accelerator pump plunger several times to expel air from pump passage.
  4. Using a small brass rod, hold discharge check ball down firmly on its seat. See Fig 1 . Raise plunger and press downward. No fuel should be emitted from either intake or discharge passage.
    Fig 1: Testing Accelerator Pump Intake & Discharge
    G8576Courtesy of CHRYSLER MOTORS.
  5. If leakage is evident, clean passage and accelerator discharge check ball seat and retest. If leakage persists, replace main body.
  6. Install replacement gaskets on venturi cluster. See Figure . Install cluster screws and tighten securely. Install main metering jets. Install floats with fulcrum pin and fulcrum retainer in main body. Install inlet needle, seat, and gasket assembly. Tighten securely.
  7. Adjust float level. Remove air horn. Hold float gently against inlet needle to raise float. Place a straightedge across float bowl to measure float level. See CARBURETOR ADJUSTMENT SPECIFICATIONS  table. See Fig 2 . If adjustment is necessary, release floats and bend float lever. Install air horn.
    NOTE: Never bend float lever while it is resting against inlet needle. Pressure may damage synthetic tip and cause incorrect adjustment.
    Fig 2: Adjusting Float Level (4.2L)
    G8567Courtesy of CHRYSLER MOTORS.
  8. Install baffle plate. Install accelerator pump ball into main body, if not previously installed. Place accelerator pump drive spring on pump plunger shaft and insert shaft into air horn. Compress spring and insert "S" link. Position replacement gasket on main body and install air horn and sole-vac solenoid.
  9. Tighten retaining screws alternately to compress gasket evenly. Place vacuum piston spring in vacuum piston bore. Install vacuum piston and metering rod assembly into air horn. Ensure that rods move freely on each side of vertical position. Rotate bowl vent assembly up and out of bowl and install vent seal, if removed.
  10. Install pump arm onto "S" link. Place 2 plastic rod lifter tangs under vacuum piston yoke. Slide accelerator pump lever shaft through rod lifter and pump arm. Install, but do not tighten, accelerator pump shaft locks and adjusting screws. Install fast idle cam, choke linkage and clip. Tighten retaining screw securely.
  11. Connect accelerator pump linkage to accelerator pump lever and throttle lever. Install retaining clip at throttle lever end of linkage. Adjust vacuum piston gap, vacuum piston, and accelerator pump.
  12. Turning adjustment screw clockwise enriches air/fuel mixture. Turning adjustment screw counterclockwise leans the air/fuel mixture. See Fig 3 . Turn adjustment screw to adjust gap to specification. See CARBURETOR ADJUSTMENT SPECIFICATIONS  table.
    Fig 3: Adjusting Vacuum Piston Gap
    G8568Courtesy of CHRYSLER MOTORS.
    NOTE: When adjusting vacuum piston and accelerator pump, it is necessary to change curb idle speed adjustment screw setting. Count and record the number of turns so the screw can be returned to its original position.
  13. Adjust vacuum piston. Turn curb idle speed adjustment screw counterclockwise until throttle valves are completely closed. Fully depress vacuum piston while holding moderate finger pressure on rod lifter tab. In this position, tighten rod lifter lock screw.
  14. Release piston and rod lifter. Adjust accelerator pump. Return curb idle speed adjustment screw to its original position. Adjust accelerator pump. Turn curb idle speed adjustment screw counterclockwise until throttle valves are completely closed.
  15. Open choke valve so that fast idle cam allows throttle valves to seat in the bores. Turn curb idle speed adjustment screw clockwise until it just barely contacts stop, then turn it in 2 complete turns more.
  16. Measure distance between surface of air horn and top of accelerator pump shaft with a "T" scale. See Fig 4 . Loosen pump arm adjusting lock screw and rotate sleeve to adjust pump travel to correct specification.
    Fig 4: Adjusting Accelerator Pump
    G8579Courtesy of CHRYSLER MOTORS.
  17. Tighten lock screw and return curb idle speed adjustment screw to its original position.
  18. Using a new gasket, install rollover check valve and bowl vent. Install diaphragm assembly and secure with attaching screws. Engage diaphragm link with slot in choke lever. Install choke lever and screw on choke shaft. Install choke housing on throttle body. Install baffle, gasket and cover on choke housing. Turn cover 1/4 turn rich and tighten one straight-slot screw.
  19. Install choke rod and clips between choke lever and choke housing lever. Adjust choke valve, fast idle cam, and choke unloader clearances. Open throttle valve slightly and place fast idle speed adjustment screw on high step of cam. Apply vacuum to force diaphragm against stop. See Fig 5 .
    Fig 5: Adjusting Choke Valve Clearance (4.2L)
    G113292Courtesy of CHRYSLER MOTORS.
  20. Measure clearance between choke valve and air horn wall with a plug gauge. See CARBURETOR ADJUSTMENT SPECIFICATIONS  table. Adjust clearance by bending vacuum diaphragm connector link.
  21. Place fast idle speed adjustment screw on second step of fast idle cam. Measure distance between choke valve and air horn wall with a plug gauge. See the CARBURETOR ADJUSTMENT SPECIFICATIONS  table. See Fig 6 . Adjust clearance by bending fast choke link down to increase distance or up to decrease distance. Install and tighten retaining screws.
    Fig 6: Adjusting Fast Idle Cam (4.2L)
    G113293Courtesy of CHRYSLER MOTORS.
  22. Hold throttle fully open and apply pressure on choke valve toward closed position. Measure clearance between lower edge of choke valve and air horn wall. See Fig 7 . Also, refer to the CARBURETOR ADJUSTMENT SPECIFICATIONS  table. Adjust clearance by bending unloader tang. DO NOT  bend unloader tang so that it binds or interferes with any other component.
    Fig 7: Adjusting Choke Unloader (4.2L)
    G113297Courtesy of CHRYSLER MOTORS.
  23. Remove choke cover screw and position cover according to color on housing. If color on housing is Gold, set choke index at zero (0). If color of housing is Red, set choke index at one notch rich. If color of housing is Green, set choke index at 2 notches rich. Tighten replacement cover screws. Install stepper motor with replacement gasket.
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