Jeep CJ/Scrambler 1971-1986 Repair Guide

Adjustments

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FLOAT AND FUEL LEVEL ADJUSTMENT



See Figures 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10

4-134 with Carter YF
  1. Remove and invert the bowl cover.
  2.  
  3. Remove the bowl cover gasket.
  4.  
  5. Allow the weight of the float to rest on the needle and spring. Be sure that there is no compression of the spring other than by the weight of the float.
  6.  
  7. Adjust the level by bending the float arm lip that contacts the needle (not the arm) to provide 17 / 64 in. (6.75mm) between the gasket surface and the tip of the float.
  8.  



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Fig. Fig. 1: Float level measurement on the Carter YF carburetor used with the 4-134 engine

4-150 with Carter YFA
  1. Remove the top of the carburetor and the gasket.
  2.  
  3. Invert the carburetor top and check the clearance from the top of the float to the bottom edge of the air horn with a float level gauge. Hold the carburetor top at eye level when making the check. The float arm should be resting on the inlet needle pin. To adjust, bend the float arm. DO NOT BEND THE TAB AT THE END OF THE ARM! See the Carburetor Specifications chart for the correct clearance.
  4.  



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Fig. Fig. 2: Measuring float clearance on the 4-150

4-151 with 2SE, E2SE

Special tools are needed for this job.

  1. Start the engine and run it to normal operating temperature.
  2.  
  3. Remove the vent stack screws and the vent stack.
  4.  
  5. Remove the air horn screw adjacent to the vent stack.
  6.  
  7. With the engine idling and the choke fully opened, carefully insert float gauge J-9789-136 for E2SE carburetors and tool J-9789-138 for 2SE carburetors, into the air horn screw hole and vent hole. Allow the gauge to rest freely on the float. DO NOT PRESS DOWN ON THE FLOAT!
  8.  
  9. With the gauge at eye level, observe the mark that aligns with the top of the casting at the vent hole. The float level should be within 1 / 16 in. (1.6mm) of the figure in the Carburetor Specifications Charts. If not, remove the air horn and adjust the float as follows:
    1. Hold the retainer pin firmly in place and push the float down, lightly, against the inlet needle.
    2.  
    3. Using an adjustable T-scale, at a point 5mm from the end of the float, at the toe, measure the distance from the float bowl top surface (gasket removed) to the top of the float at the toe. The distance should be that shown in the Carburetor Specifications Charts. If not, remove the float and bend the arm.
    4.  

  10.  



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Fig. Fig. 3: Float adjustment on the 2SE and E2SE carburetors

6-225 with Rochester 2G

The procedure for adjusting the float level of the two barrel carburetor installed on the V6 is the same as the procedure for the 4-134 up to step 4.

The actual measurement is taken from the air horn gasket to the lip at the toe of the float. This distance should be 5 / 32 in. (4mm). To adjust the float level, bend the float arm as required.

The float drop adjustment is accomplished in the following manner: With the bowl cover turned in the upright position, measure the distance from the gasket to the notch at the toe of the float. Bend the tang as required to obtain a measurement of 1 7 / 32 in. (31mm).



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Fig. Fig. 4: Float drop adjustment on the 6-225 engine



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Fig. Fig. 5: Float level adjustment on the 6-225 engine

6-232 and 6-258 with Carter YF

Remove and invert the air horn assembly and remove the gasket. Measure the distance between the top of the float at the free end, and the air horn casting. The measurement should be 29 / 64 - 31 / 64 in. (11.5-12.3mm). Adjust by bending the float lever.

The fuel inlet needle must be held off its seat while bending the float lever in order to prevent damage to the needle and seat.

To adjust the float drop, hold the air horn in the upright position and measure the distance between the top of the float, at the extreme outer end, and the air horn casting. The measurement should be 1 1 / 4 in. (31.75mm) to 1973, 1 3 / 8 in. (35mm) 1974-78. Adjust by bending the tab at the rear of the float lever.



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Fig. Fig. 6: Float adjustment on the Carter YF carburetor used on the 6-232 and 6-258 engines



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Fig. Fig. 7: Carter YF float drop adjustment

6-258 with Carter BBD 2-bbl
  1. Remove the air horn.
  2.  
  3. Apply light finger pressure to the vertical float tab to exert GENTLE pressure against the inlet needle.
  4.  
  5. Lay a straight edge across the float bowl and measure the gap between the straight edge and the top of the float at its highest point. The gap should be 1 / 4 in. (6mm).
  6.  
  7. To adjust, remove the float and bend the lower tab. Replace the float and check the gap.
  8.  



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Fig. Fig. 8: Float adjustment on the Carter BBD carburetor

8-304 with Autolite 2100/Motorcraft 2150-Dry Adjustment

With the air horn assembly and the gasket removed raise the float by pressing down on the float tab until the fuel inlet needle is lightly seated. Using a T-scale, measure the distance from the fuel bowl machined surface to either corner of the float 1 / 8 in. (3mm) from the free end. The measurement should be 3 / 4 in. (19mm) through 1975, 3 / 16 , 15 / 32 in. (5-12mm) 1976-81. To adjust bend the float tab and hold the fuel inlet needle off its eat in order to prevent damage to the seat and the tip of the needle.



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Fig. Fig. 9: Autolite 2100 and Motorcraft 2150 dry float adjustment

8-304 with Motorcraft 2150-Wet Adjustment

Exercise extreme care when performing this adjustment as fuel vapors and liquid fuel are present!

  1. Place the vehicle on a flat, level surface and run the engine to normal operating temperature. Turn off the engine and remove the air cleaner.
  2.  
  3. Remove the air horn attaching screws, but leave the air horn in place.
  4.  
  5. Start the engine and let it idle for one minute. Shut off the engine and remove the air horn and gasket.
  6.  
  7. Use a T-scale to measure the vertical distance between the machined surface of the carburetor body and the fuel level in the bowl. Make this measurement as near the center of the bowl as possible. The proper distance is 59 / 64 in. (23.4mm). To adjust, bend the float tab.
  8.  

Every time an adjustment is made, the air horn must be replaced, and the engine started and idled for one minute to stabilize the fuel level.

  1. Install the air horn and gasket when adjustment is completed.
  2.  



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Fig. Fig. 10: Motorcraft 2150 wet float adjustment

FAST IDLE LINKAGE ADJUSTMENT



See Figures 11, 12, 13, 14 and 15

This adjustment is performed with the air cleaner removed.

4-134 with Carter YF

With the choke held in the wide open position, the lip on the fast idle rod should contact the boss on the body casting. Adjust it by bending the fast idle link at the offset in the link.

4-150 Engine
  1. Run the engine to normal operating temperature. Connect a tachometer according to the maker's instructions.
  2.  
  3. Disconnect and plug the EGR valve vacuum hose.
  4.  
  5. Position the fast idle adjustment screw on the second stop of the fast idle cam with the transmission in neutral.
  6.  
  7. Adjust the fast idle speed to 2300 rpm for auto. trans. and 2000 rpm for man. trans.
  8.  
  9. Idle the engine and reconnect the EGR hose.
  10.  



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Fig. Fig. 11: Carter YFA fast idle adjustment, (d) is the fast idle cam screw, (e) is the second step and (f) is the cam

4-151 with Rochester 2SE, E2SE
  1. Make sure the choke coil adjustment is correct and that the fast idle speed is correct.
  2.  
  3. Obtain a Choke Angle Gauge, tool #J-26701-A. Rotate the degree scale to the zero degree mark opposite the pointer.
  4.  
  5. With the choke valve completely closed, place the magnet on the tool squarely on the choke plate. Rotate the bubble unit until it is centered.
  6.  
  7. Rotate the degree scale until the 25 degree mark is opposite the pointer. On carburetors with choke cover sticker number 70172, the angle is 18 degrees.
  8.  
  9. Place the fast idle screw on the second step of the cam.
  10.  
  11. Close the choke plate by pushing on the intermediate choke lever.
  12.  
  13. Push the vacuum brake lever toward the open choke position until the lever is against the rear tank on the choke lever.
  14.  
  15. Adjust by bending the fast idle cam rod until the bubble is centered.
  16.  



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Fig. Fig. 12: Fast idle cam position adjustment on the 2SE and E2SE carburetors



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Fig. Fig. 13: Carter YF fast idle adjustment on the 6-232 and 6-258 engines

6-225 with Rochester 2G

No fast idle speed adjustment is required. Fast idle is controlled by the curb adjustment screw. If the curb idle speed is set correctly and the choke rod is properly adjusted, fast idle speed will be correct.

6-232, 6-258 through 1973 with Carter YF

Partially open the throttle and close the choke valve to rotate the fast idle cam into the cold start position. While holding the choke valve closed, release the throttle. With the fast idle cam in this position, the fast idle adjusting screw must be aligned with the index mark at the back side of the cam. Adjust by bending the choke rod at its upper angle.

6-232, 6-258 1974-78 with Carter YF

Position the fast idle screw on the second step of the fast idle cam, against the shoulder of the high step on the cam. Adjust by bending the choke plate connecting rod to obtain 13 / 64 in. (5mm) clearance between the lower edge of the choke plate and the air horn wall.

6-258 with Carter BBD 2-bbl
  1. Loosen the choke housing cover and turn it 1 / 4 turn right. Tighten one screw.
  2.  
  3. Slightly open the throttle and place the fast idle screw on the second cam step.
  4.  
  5. Measure the distance between the choke plate and the air horn wall. The distance should be 0.095 in.
  6.  
  7. If adjustment is necessary, bend the fast idle cam link down to increase and up to decrease the gap.
  8.  
  9. Return the choke cover cap to the original setting.
  10.  



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Fig. Fig. 14: Fast idle cam adjustment on the Carter BBD carburetor

8-304 with Autolite 2100, Motorcraft 2150

Push down on the fast idle cam lever until the fast idle speed adjusting screw is contacting the second step (index), and against the shoulder of the high step. Measure the clearance between the lower edge of the choke valve and air horn wall. Adjust by turning the fast idle cam lever screw to obtain 19 / 64 in. (7.5mm) through 1975 and 1 / 8 in. (3mm) 1976-79. Adjust the automatic choke.



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Fig. Fig. 15: Fast idle cam index setting for the Autolite 2100 carburetor

INITIAL CHOKE VALVE CLEARANCE



See Figures 16 and 17

  1. Position the fast idle screw on the top step of the fast idle cam.
  2.  
  3. Using a vacuum pump, seat the choke vacuum break.
  4.  
  5. Apply light closing pressure in the choke plate to position the plate as far closed as possible without forcing it.
  6.  
  7. Measure the distance between the air horn wall and the choke plate. If it is not that specified in the Carburetor Specifications Chart, bend the choke vacuum break link until it is.
  8.  



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Fig. Fig. 16: Motorcraft 2150 initial choke valve clearance adjustment



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Fig. Fig. 17: Choke coil lever adjustment on the 2SE and E2SE carburetor

CHOKE SETTING ADJUSTMENT



4-134 and 6-225 Engines

The choke is manually operated by a cable that runs from the dash mounted control pull knob to the set screw on the choke actuating arm. To adjust the choke, loosen the set screw at the choke actuating lever and push in the dash knob as far as it will go. Open the choke plate as far as it will go and hold it with your finger while the set screw is tightened.

6-232, 258 and 8-304 Engines

The automatic choke setting is made by loosening the choke cover in the desired direction as indicated by an arrow on the face of the cover. the original setting will be satisfactory for most driving conditions. However, if the engine stumbles or stalls on acceleration during warmup, the choke may be set richer or leaner no more than two graduations from the original setting.

4-150 and 4-151 Engines

Once the rivets and choke cover are removed, a choke cover retainer kit is necessary for assembly.

  1. Remove the rivets, retainers, choke cover and coil following the instructions found in the cover retainer kit.
  2.  
  3. Position the fast idle adjustment screw on the highest stop of the fast idle cam.
  4.  
  5. Push on the intermediate choke lever and close the choke plate.
  6.  
  7. Insert the proper plug gauge, 0.050-0.080 in. (1.27-2.032mm) for manual trans. and 0.85 in. (21.6mm) for automatic trans., in the hole adjacent to the coil lever. The edge of the lever should barely contact the plug gauge.
  8.  
  9. Bend the intermediate choke rod to adjust.
  10.  

UNLOADER ADJUSTMENT



See Figures 18, 19, 20, 21 and 22

6-232 and 6-258 Engines

With the throttle held fully open, apply pressure on the choke valve toward the closed position and measure the clearance between the lower edge of the choke valve and the air horn wall. The measurement should be 1 / 4 in. (6mm) for 1972-73, 7mm for 1974-86. Adjust by bending the tang on the throttle lever which contacts the fast idle cam. Bend toward the cam to increase the clearance.

Do not bend the unloader down from a horizontal plane. After making the adjustment, make sure the unloader tang does not contact the main body flange when the throttle is fully open. A clearance of 0.070 in. (1.8mm) must be present. Final unloader adjustment must always be done on the vehicle. The throttle should be fully opened by depressing the accelerator pedal to the floor. This is to assure that full throttle is obtained.

4-150 and 4-151 Engines
  1. Obtain a Carburetor Choke Angle Gauge, tool #J-26701-A. Rotate the scale on the gauge until the 0 mark is opposite the pointer.
  2.  
  3. Close the choke plate completely and set the magnet squarely on top of it.
  4.  
  5. Rotate the bubble until it is centered.
  6.  
  7. Rotate the degree scale until the correct specification is obtained.
  8.  
  9. Hold the primary throttle valve wide open.
  10.  
  11. Bend the throttle lever tang until the bubble is centered.
  12.  

6-225 and 8-304 Engines

With the throttle held fully open, apply pressure on the choke valve toward the closed position and measure the clearance between the lower edge of the choke valve and the air horn wall. The setting should be 1 / 4 in. (6mm); 5 / 16 in. (8mm) for 1979. Adjust by bending the tang on the fast idle lever, which is located on the throttle linkage. Refer to the "Note'' under the procedure for adjusting the unloader on the Sixes.



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Fig. Fig. 18: Carter YF choke unloader adjustment



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Fig. Fig. 19: Choke unloader adjustment on the 2SE and E2SE carburetors



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Fig. Fig. 20: Motorcraft 2150 choke unloader adjustment



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Fig. Fig. 21: Motorcraft 2150 choke unloader/fast idle cam clearance



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Fig. Fig. 22: Rochester 2GV choke unloader adjustment

DASHPOT ADJUSTMENT



See Figures 23 and 24

6-232, 6-258 and 8-304 Engines

With the throttle set at curb idle position fully depress the dashpot stem and measure the clearance between the stem and the throttle lever. Adjust by loosening the lock nut and turning the dashpot.

4-134 and 6-225 Engines

The adjustment is made with the engine idling. Loosen the dashpot locknut and turn the assembly until the plunger contacts the throttle lever without being depressed. Then, turn the assembly 2 1 / 2 turns against the lever, depressing the plunger. Tighten the locknut.



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Fig. Fig. 23: Dashpot adjustment for the Rochester 2GV carburetor



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Fig. Fig. 24: Choke rod adjustment for the Rochester 2GV carburetor

VACUUM (STEP UP) PISTON GAP



See Figures 25, 26, 27, 28 and 29

Carter BBD
  1. Turn the adjusting screw, mounted on top of the unit, so that the gap between the metering rod lifter lower edge, and the top of the vacuum piston, is as specified in the Carburetor Specifications Charts.
  2.  
  3. Counting the number of turns involved, turn the curb idle adjustment screw counterclockwise, until the throttle valves are completely closed.
  4.  
  5. Fully depress the vacuum piston, while exerting moderate pressure on the metering rod lifter tab. In this position, tighten the rod lifter lock screw.
  6.  
  7. Release the piston and rod lifter.
  8.  

The accelerator pump should now be adjusted.

  1. Return the curb idle adjustment screw to its original position.
  2.  



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Fig. Fig. 25: Carter BBD vacuum piston gap adjustment



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Fig. Fig. 26: Carter BBD accelerator pump adjustment



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Fig. Fig. 27: Motorcraft/Autolite 2100, 2150 accelerator pump adjustment points



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Fig. Fig. 28: After removing the accelerator pump cover, the return spring can be removed



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Fig. Fig. 29: The accelerator pump diaphragm can be replaced, with the carburetor mounted on the engine

ACCELERATOR PUMP



See Figure 30

Carter BBD
  1. Counting the number of turns involved, turn the curb idle adjustment screw counterclockwise, until the throttle valves are completely closed.
  2.  
  3. Open the choke valve so that the fast idle cam will allow the throttle valves to seat in their bores.
  4.  
  5. Turn the curb idle adjustment screw clockwise, so that it just barely touches the stop, then, turn it 2 full turns further.
  6.  
  7. Measure the distance between the surface of the air horn and the top of the accelerator pump shaft with a T-scale. The distance should be 33 / 64 in. (13mm).
  8.  
  9. If the dimension is not correct, loosen the pump arm adjusting screw and rotate the sleeve to adjust the pump travel. Tighten the lock screw.
  10.  
  11. Return the curb idle screw to its original position.
  12.  

Autolite/Motorcraft 2100 and 2150

Under normal driving conditions, the pump rod should be in the inboard hole of the pump actuating lever and the third hole (counting from the bottom up) of the overtravel lever.

Under extremely hot conditions, the rod should be placed in the second hole of the overtravel lever.

Under extremely cold conditions, the rod should be placed in the fourth hole of the overtravel lever.



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Fig. Fig. 30: Metering rod adjustment on the Carter YFA carburetor

METERING ROD



Carter YFA
  1. Remove the air horn and gasket.
  2.  
  3. Make sure that the idle speed adjustment screw allows the throttle plate to close tightly in the bore.
  4.  
  5. Press down on the top of the pump diaphragm shaft until it bottoms.
  6.  
  7. In this position, adjust the metering rod by turning the adjusting screw counterclockwise, until the metering rod lightly bottoms in the main metering jet.
  8.  
  9. Turn the adjusting screw 1 full turn more.
  10.  
  11. Install the air horn and gasket, and adjust the curb idle speed.
  12.  

 
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