Chevrolet Chevette/1000 1976-1988 Repair Guide

Carburetor

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REMOVAL & INSTALLATION





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Fig. Fig. 1Carburetor and EFE mounting-1980-88 vehicles



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Fig. Fig. 2Unfasten the carburetor retaining bolts, then ...



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Fig. Fig. 3... remove the carburetor from the vehicle. Note that the EFE heater grid is located under the carburetor


CAUTION
Never smoke when working around gasoline! Avoid all sources of sparks or ignition. Gasoline vapors are EXTREMELY volatile!

  1. Remove the air cleaner.
  2.  
  3. Disconnect the fuel line. Disconnect all vacuum lines, but note where they attach.
  4.  
  5. Disconnect the electrical connector at the choke.
  6.  
  7. Disconnect the accelerator linkage.
  8.  
  9. Disconnect the solenoid electrical connector.
  10.  
  11. On cars with an automatic transmission, disconnect the detent cable.
  12.  
  13. Remove the carburetor retaining nuts and remove the carburetor/solenoid assembly.
  14.  
  15. On 1980-88 models remove the electric EFE insulator gasket.
  16.  
  17. Installation is the reverse of removal. Start the engine and check for leaks.
  18.  

FLOAT LEVEL ADJUSTMENT





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Fig. Fig. 4Float level adjustment-1976-78 vehicles



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Fig. Fig. 5Float level adjustment-1979-88 vehicles

  1. Remove the top of the carburetor.
  2.  


CAUTION
Never smoke when working around gasoline! Avoid all sources of sparks or ignition. Gasoline vapors are EXTREMELY volatile!

  1. Hold the float retaining pin in place and push down on the float arm at the outer end against the top of the float needle valve.
  2.  
  3. Measure the distance from the bump on the top of the float at the end to the bowl gasket surface, without the gasket.
  4.  
  5. To adjust, bend the float arm at the point where it joins the float.
  6.  

METERING ROD ADJUSTMENT



1976-78 Vehicles


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Fig. Fig. 6Metering rod adjustment

  1. Remove the top of the carburetor.
  2.  


CAUTION
Never smoke when working around gasoline! Avoid all sources of sparks or ignition. Gasoline vapors are EXTREMELY volatile!

  1. Back out the idle stop solenoid and rotate the fast idle cam so that the fast idle screw does not contact the cam.
  2.  
  3. With the throttle valve completely closed, make sure that the power piston is all the way up.
  4.  
  5. Insert the specified size gauge between the bowl gasket surface with no gasket and the lower surface of the metering rod holder, next to the metering rod.
  6.  
  7. To adjust, carefully bend the metering rod holder.
  8.  

FAST IDLE SPEED ADJUSTMENT





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Fig. Fig. 7Location of the fast idle adjusting screw for 1979-88 vehicles

  1. The engine should be at normal temperature with the air cleaner in place. On 1976-78 models, disconnect and plug the EGR valve vacuum line. On 1979 and later models disconnect and plug the EGR port at the carburetor.
  2.  
  3. Make sure that the curb idle speed is as specified using a tachometer.
  4.  
  5. Place the fast idle screw on the highest cam step with the engine running.
  6.  
  7. Adjust the fast idle speed screw to the correct fast idle speed.
  8.  

FAST IDLE CAM ADJUSTMENT



1976-78 Vehicles


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Fig. Fig. 8Fast idle cam adjustment-1976-78 vehicles

  1. Hold the fast idle speed screw on the second cam step against the shoulder of the high step.
  2.  
  3. Hold the choke valve closed with a finger.
  4.  
  5. Insert the specified gauge between the center upper edge of the choke valve and the air horn wall.
  6.  
  7. Bend the linkage rod at the upper angle to adjust.
  8.  

1979-88 Vehicles


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Fig. Fig. 9Fast idle cam adjustment-1979-88 vehicles

  1. Set the fast idle cam so that the screw is held against the second high step of the cam.
  2.  
  3. Insert the specified gauge between the lower edge of the choke valve and the inside air horn wall.
  4.  
  5. Bend the tang to adjust.
  6.  

VACUUM BREAK ADJUSTMENT



1976-78 Vehicles


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Fig. Fig. 10Vacuum break adjustment-1976-78 vehicles

  1. Place the fast idle speed screw on the highest cam step.
  2.  
  3. Tape over the bleed hole in the diaphragm unit. Apply suction by mouth to seat the diaphragm.
  4.  
  5. Push down on the choke valve with a finger.
  6.  
  7. Insert the gauge between the upper edge of the choke valve and the air horn wall.
  8.  
  9. Bend the link to adjust.
  10.  

1979 Vehicles


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Fig. Fig. 11Vacuum break adjustment-1979 vehicles

  1. Position the fast idle cam by opening throttle 1 / 3 open, manually closing choke plate, then closing throttle. Check to see that fast idle screw rests on top step.
  2.  
  3. Note position of choke index. Remove the three screws and ring retaining the choke assembly. Unplug wire from choke housing and remove entire choke assembly as a unit (bimetal assembly, grounding ring, nylon eye, and plastic housing).
  4.  
  5. With a screwdriver or suitable tool, push diaphragm shaft against stop.
  6.  
  7. Take slack out of linkage by holding the choke housing shaft tang (the tang that mates with the bimetal eye) in the direction of the choke plate closing.
  8.  
  9. Insert a specified gauge between lower edge of choke and air horn wall (with no weight on the choke plates).
  10.  
  11. Turn adjusting screw in or out with an Allen wrench to obtain specified clearance.
  12.  
  13. After adjustment, reassemble in the following sequence: plastic core housing, grounding ring, nylon eye, bimetal assembly, retaining ring, 3 attaching screws. Rotate the bimetal cover making sure choke valves operate in both directions without interference of binding. Return index on bimetal cover to original position and tighten screws to 7 in. lbs. Plug wire back onto choke housing.
  14.  

1980-88 Vehicles


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Fig. Fig. 12Vacuum break adjustment-1980-88 vehicles

  1. Apply an external vacuum source and seat the vacuum break diaphragm.
  2.  
  3. Push the fast idle cam lever down (clockwise) to close the choke valve.
  4.  
  5. Take the slack out of the linkage in the open choke direction.
  6.  
  7. Insert the specified gauge between the lower edge of the choke valve and the inside air horn wall. Hold the gauge vertical.
  8.  
  9. Turn the adjusting screw to obtain the clearance.
  10.  

STEPPED SPEED CONTROL SYSTEM (SSC)



1983-88 Vehicles


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Fig. Fig. 13Stepped speed control adjustment-1983-88 vehicles equipped with A/C



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Fig. Fig. 14Stepped speed control adjustment-1983-88 vehicles without A/C

For the SSC adjustment, please refer to the illustrations.

CHOKE UNLOADER ADJUSTMENT



1976-78 Vehicles


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Fig. Fig. 15Choke unloader adjustment-1976-78 vehicles

  1. Hold the throttle valve wide open.
  2.  
  3. Hold-down the choke valve with a finger and insert the specified gauge between the upper edge of the choke valve and the inside air horn wall.
  4.  
  5. Bend the linkage tang to adjust.
  6.  

1979-88 Vehicles


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Fig. Fig. 16Choke unloader adjustment-1979-88 vehicles

  1. Position the throttle lever to wide-open.
  2.  
  3. Insert the specified gauge between the lower edge of the choke valve and the inside air horn wall. Hold the gauge vertical.
  4.  
  5. Bend the tang at the existing radius to adjust.
  6.  

CHOKE COIL LEVER ADJUSTMENT



1976-78 Vehicles


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Fig. Fig. 17Choke coil cover adjustment-1976-78 vehicles

  1. Place the fast idle speed screw on the highest cam step.
  2.  
  3. Hold the choke valve closed.
  4.  
  5. Insert a 3mm gauge through the hole in the arm on the choke housing and into the hole in the casting.
  6.  
  7. Bend the link to adjust.
  8.  

ELECTRIC CHOKE ADJUSTMENT



1976-78 Vehicles


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Fig. Fig. 18Electric choke adjustment-1976-78 vehicles

  1. Place the fast idle cam follower on the high step.
  2.  
  3. Loosen the three retaining screws and rotate the cover counterclockwise until the choke valve just closes.
  4.  
  5. Align the index mark on the cover with the specified housing mark.
  6.  
  7. Tighten the three screws.
  8.  

1979 Vehicles


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Fig. Fig. 19Electric choke adjustment-1979 vehicles

  1. Loosen the retaining screws.
  2.  
  3. With the choke coil lever located inside the coil tang set the mark on the choke coil assembly to the specified point on the choke housing. Retighten the retaining screws.
  4.  

OVERHAUL





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Fig. Fig. 20Exploded view of a carburetor-1983 vehicle shown (part 1 of 2)



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Fig. Fig. 21Carburetor component key list-1983 vehicle shown (part 2 of 2)



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Fig. Fig. 22Carburetor Specifications



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Fig. Fig. 23Carburetor Specifications (cont.)

Efficient carburetion depends greatly on careful cleaning and inspection during overhaul since dirt, gum, water or varnish in or on the carburetor parts are often responsible for poor performance.

Overhaul the carburetor in a clean, dust free area. Carefully disassembly the carburetor, referring often to the exploded views. Keep all similar and look-alike parts segregated during disassembly and cleaning to avoid accidental interchange during assembly. Make a note of all jet sizes.

When the carburetor is disassembled, wash all parts (except diaphragms, electric choke units, pump plunger and any other plastic, leather, fiber, or rubber parts) in clean carburetor solvent. Do not leave the parts in the solvent any longer than is necessary to sufficiently loosen the dirt and deposits. Excessive cleaning may remove the special finish from the float bowl and choke valve bodies, leaving these parts unfit for service. Rinse all parts in clean solvent and blow them dry with compressed air or allow them to air dry, while resting on clean, lintless paper. Wipe clean all cork, plastic, leather and fiber parts with clean, lint free cloth.

Blow out all passages and jets with compressed air and be sure that there are no restrictions or blockages. Never use wire or similar tools to clean jets, fuel passages or air bleeds. Clean all jets and valves separately to avoid accidental interchange.

Examine all parts for wear or damage. If wear or damage is found, place the defective parts. Especially, inspect the following:

  1. Check the float needle and seat for wear. If wear is found, replace the complete assembly.
  2.  
  3. Check the float hinge pin for wear and the float(s) for dents or distortion, replace the float if fuel has leaked into it.
  4.  
  5. Check the throttle and choke shaft bores for wear or an out-of-round condition. Damage or wear to the throttle arm, shaft or shaft bore will often require replacement of the throttle body. These parts require a close tolerance of fit; wear may allow air leakage, which could affect starting and idling.
  6.  

Throttle shaft and bushings are not normally included in overhaul kits. They can be purchased separately.

  1. Inspect the idle mixture adjusting needles for burrs and grooves. Any such condition requires replacement of the needle, since you will not be able to obtain a satisfactory idle.
  2.  
  3. Test the accelerator pump check valves. They should pass air one way, but not the other. Test for proper seating by blowing and sucking on the valve. Replace the valve as necessary. If the valve is satisfactory, wash the valve again to remove moisture.
  4.  
  5. Check the bowl cover for warped surfaces with a straightedge.
  6.  
  7. Closely inspect the valves and seats for wear and damage, replacing as necessary.
  8.  
  9. After the carburetor is assembled, check the choke valve for freedom of operation.
  10.  

Carburetor overhaul kits are recommended for each overhaul, these kits contain all gaskets and new parts to replace those which deteriorate most rapidly. Failure to replace all of the parts supplied with the kit (especially gaskets) can result in poor performance later.

Most carburetor manufacturers supply overhaul kits of three basic types: minor repair; major repair; and gasket kits. Basically, they contain the following:

Minor Repair Kits:


All gaskets
 
Float needle valve
 
All diagrams
 
Spring for the pump diaphragm
 

Major Repair Kits:


All jets and gaskets
 
All diaphragms
 
Float needle valve
 
Pump ball valve
 
Float
 
Complete intermediate rod
 
Intermediate pump lever
 
Some cover hold-down screws and washers
 

Gasket kits:


All gaskets
 

After cleaning and checking all components, reassemble the carburetor, using new parts and referring to the exploded view. When reassembling, make sure that all screws and jets are right in their seat, but do not overtighten, as the tip will be distorted. Tighten all screws gradually, in rotation. Do not tighten needle valves into their seats; uneven jetting will result. Always use new gaskets. Be sure to adjust the float level.

Most carburetor rebuilding kits contain a sheet of specific instructions pertaining to the carburetor the kit is for.

 
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