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    Chrysler Full-Size Vans 1967-1988 Repair Guide

    Rochester Quadrajet

    Print

    ADJUSTMENTS



    Float Level
    EXTERNAL CHECK

    See Figure 1



    Click image to see an enlarged view

    Fig. Fig. 1: Float level external check for the Rochester Quadrajet

    1. With the engine idling at normal operating temperature and the choke wide open, insert float gauge C-4900 in the vent hole and allow the gauge to float freely. DO NOT PRESS DOWN ON THE GAUGE, AS THIS WILL RESULT IN FLOODING AND/OR FLOAT DAMAGE!
    2.  
    3. Look at the mark on the gauge that lines up with the top of the casting. The reading should be 13 / 32 " +-1 / 16 ".
    4.  
    5. If not, remove the air horn and set the float as described immediately following.
    6.  

    Setting

    See Figure 2



    Click image to see an enlarged view

    Fig. Fig. 2: Float level adjustment for the Quadrajet carburetor

    1. Remove the air horn, gasket and power piston, and plastic float bowl insert.
    2.  
    3. Hold the float bowl retainer firmly in place.
    4.  
    5. Push the float down [cf2]lightly against the needle.
    6.  
    7. Measure the float height from the top of the casting to the top of the float at a point 3 / 16 " from the end of the float. The height should be 13 / 32 ".
    8.  
    9. If the float level is too high, hold the retainer in place and push down on the center of the float pontoon to get the correct setting.
    10.  
    11. If the float level is too low, bend the float upward to get the correct setting.
    12.  
    13. Recheck the float level.
    14.  
    15. Install the bowl insert, power piston and gasket, and air horn.
    16.  

    Air Valve Spring

    See Figure 3



    Click image to see an enlarged view

    Fig. Fig. 3: Air valve spring adjustment for the Quadrajet carburetor

    1. Using a 3 / 32 " wrench, loosen the air valve spring lockscrew.
    2.  
    3. Turn the tension adjusting screw counterclockwise until the air valve opens part way.
    4.  
    5. Turn the screw clockwise the following number of turns:

      17085408- 1 / 2 turn
       
      17085409- 5 / 8 turn
       
      17085415- 1 / 2 turn
       
      17085417- 3 / 4 turn
       
      17086425- 1 / 2 turn
       
      17087245- 5 / 8 turn
       
      17087176- 3 / 4 turn
       
      17087175- 3 / 4 turn
       
      17087177-1 turn
       
      17085431- 1 / 2 turn
       

    6.  
    7. Hold the adjusting screw and tighten the locknut.
    8.  
    9. Apply a light film of lithium based grease to the contact area.
    10.  

    Choke Coil Lever

    See Figure 4



    Click image to see an enlarged view

    Fig. Fig. 4: Choke coil lever adjustment for the Quadrajet carburetor

    1. Remove the choke cover.
    2.  
    3. Place the fast idle cam follower on the highest step of the cam.
    4.  
    5. Push up on the choke coil lever to close the choke plate.
    6.  
    7. Insert a 0.120" drill bit in the hole just below the choke coil lever. The lower edge of the lever should [cf2]just contact the drill bit.
    8.  
    9. If not, bend the choke rod at the upper angle.
    10.  

    Fast Idle Cam

    See Figure 5



    Click image to see an enlarged view

    Fig. Fig. 5: Fast idle cam adjustment for the Quadrajet carburetor

    1. Attach a rubber band to the green tang of the intermediate choke shaft.
    2.  
    3. Open the throttle to allow the choke valve to close.
    4.  
    5. Place the cam follower on the second step of the cam. If the cam follower won't touch the cam, turn the fast idle speed screw in until it does.
    6.  
    7. Apply a slight opening pressure on the choke plate and insert a 0.143 drill bit between the top of the choke plate and the air horn wall. A slight drag should be felt on the drill bit.
    8.  
    9. If adjustment is needed, bend the tang of the fast idle cam.
    10.  

    Choke Vacuum Kick

    See Figure 6



    Click image to see an enlarged view

    Fig. Fig. 6: Vacuum kick adjustment for the Quadrajet carburetor

    1. Attach a rubber band to the green tang of the intermediate choke shaft.
    2.  
    3. Open the throttle to allow the choke valve to close.
    4.  
    5. Using a vacuum pump, apply at least 18 in.Hg to the nipple on the choke diaphragm. The air valve rod must not restrict the plunger from fully retracting. If necessary, bend the rod to permit full plunger travel. The final rod clearance must be set after the vacuum kick setting has been made.
    6.  
    7. With the vacuum still applied, apply a slight opening pressure on the choke plate and insert a 0.214" drill bit between the top of the choke plate and the air horn casting on all 1985 models; 0.170" on all 1986 models; on 1987-88 models, the drill bit should be 0.150" for 49s models, 0.170 for high altitude models, or 0.140" for California and Canada models. A slight drag should be felt.
    8.  
    9. If adjustment is necessary, bend the link at the upper angle.
    10.  

    Air Valve Rod

    See Figure 7



    Click image to see an enlarged view

    Fig. Fig. 7: Air valve rod adjustment for the Quadrajet carburetor

    1. Using a vacuum pump, apply at least 18 in.Hg to the vacuum nipple on the choke vacuum diaphragm.
    2.  
    3. Close the air valve.
    4.  
    5. Insert a 0.025" drill bit between the rod and the end of the slot. The drill bit should [cf2]just fit.
    6.  
    7. To adjust, bend the rod at the lower left angle.
    8.  

    Choke Unloader

    See Figure 8



    Click image to see an enlarged view

    Fig. Fig. 8: Choke unloader adjustment on the Quadrajet carburetor

    1. Attach a rubber band to the green tang of the intermediate choke shaft.
    2.  
    3. Open the throttle to allow the choke plate to close.
    4.  
    5. Hold the secondary lockout lever away from the pin.
    6.  
    7. Hold the throttle lever in the wide open position.
    8.  
    9. Apply a slight opening pressure on the choke plate and insert a 0.345" drill bit between the top of the choke plate and the air horn wall for all 1985 models; 0.260" for all 1986 models; for 1987-88 models use a 0.200" drill bit for 49 states models, 0.220" for high altitude models; 0.209" for California and Canada models. A slight drag should be felt.
    10.  
    11. If adjustment is required, bend the tang of the fast idle lever.
    12.  

    Secondary Lockout

    See Figure 9



    Click image to see an enlarged view

    Fig. Fig. 9: Secondary lockout adjustment on the Quadrajet carburetor

    LOCKOUT LEVER
    1. Close the choke plate.
    2.  
    3. Close the throttle plates.
    4.  
    5. Insert a 0.015" drill bit between the lockout lever and the secondary throttle plate actuating pin. The drill bit should [cf2]just fit. If not, bend the pin.
    6.  

    LOCKOUT OPENING CLEARANCE
    1. Hold the choke plate wide open by pushing down on the tail of the fast idle cam.
    2.  
    3. Insert a 0.015" drill bit between the end of the lockout lever and the end of the secondary throttle actuating pin. The drill bit should [cf2]just fit. If not, file the end of the pin.
    4.  

    Fast Idle Speed

    See Figure 10



    Click image to see an enlarged view

    Fig. Fig. 10: Fast idle speed adjustment on the Quadrajet carburetor

    1. Run the engine to normal operating temperature.
    2.  
    3. Disconnect and plug the EGR vacuum line and distributor advance vacuum line. Disconnect and plug the 3 / 16 " vacuum hose at the canister. Remove the PCV valve from the rocker cover and allow it to draw fresh air.
    4.  
    5. Set the parking brake and place the transmission in Neutral.
    6.  
    7. With the engine off, open the throttle and place the fast idle adjusting screw on the second highest speed step of the cam.
    8.  
    9. Start the engine. Let the engine speed stabilize.
    10.  
    11. Turn the fast idle speed screw in or out until the engine speed listed on the underhood sticker is reached.
    12.  
    13. Reposition the screw on the cam after each adjustment to provide the correct closing torque.
    14.  
    15. Reconnect the vacuum hoses and install the air cleaner.
    16.  

     
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