Dodge Omni/Horizon/Rampage 1978-1989 Repair Guide

Carburetor

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Holley models 5220 and 6520 are used. Each unit is a staged 2-barrel unit.

ADJUSTMENTS




WARNING
Before attempting any adjustments, complaints of fuel loading on a cold engine on all 1978 models (except those with Federal emission package and aspirator and manual transaxle) can be cured by removing the secondary choke blade and choke blade attaching screws and discarding. This change has been incorporated in production as of May 15, 1978.

Fast Idle
  1. Remove the top of the air cleaner.
  2.  
  3. Detach and plug the EGR vacuum line. On 2.2L engines, disconnect the 2-way electrical harness at the carburetor (red and tan wires).
  4.  



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Fig. Fig. 1 Fast idle speed adjusting screw location

  1. Plug any open vacuum lines, which were connected to the air cleaner.
  2.  
  3. Do not disconnect the vacuum line to the spark control computer. Instead, use a jumper wire to ground the idle stop switch. The air conditioning should be off.
  4.  
  5. Disconnect the engine cooling fan at the radiator and complete the circuit at the plug with a jumper wire to energize the fan.
  6.  
  7. Set the brake, place the transaxle in Neutral and position the first step of the fast idle cam under the adjusting screw.
  8.  
  9. Connect a tachometer according to the manufacturer's specifications.
  10.  
  11. Start the engine and observe the idle speed. With the choke fully open, the speed should remain steady. If it gradually increases, the idle stop switch is not properly grounded.
  12.  
  13. Turn the adjusting screw to give the specified rpm. Do not adjust with the screw contacting the plastic cam.
  14.  
  15. Operate the throttle linkage a few times and return the screw to the first cam step to recheck rpm.
  16.  

Float Setting and Float Drop
  1. Remove and invert the air horn.
  2.  
  3. Insert a 15 / 32 in. (12mm) gauge between the air horn and float.
  4.  
  5. If necessary, bend the tang on the float arm to adjust.
  6.  



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Fig. Fig. 2 Adjust the float by bending the adjustment tang

  1. Turn the air horn right side up and allow the float to hang freely. Measure the float drop from the bottom of the air horn to the bottom of the float. It should be exactly 55 / 64 in. (22mm). Correct by bending the float tang, do this with a screwdriver.
  2.  

Vacuum Kick
  1. Open the throttle, close the choke, then close the throttle to trap the fast idle system at the closed choke position.
  2.  
  3. Disconnect the vacuum hose to the carburetor and connect it to an auxiliary vacuum source.
  4.  
  5. Apply at least 15 in. Hg (51 kPa) vacuum to the unit.
  6.  
  7. Apply sufficient force to close the choke valve without distorting the linkage.
  8.  
  9. Insert a gauge (see Specification Chart) between the top of the choke plate and the air horn wall.
  10.  



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Fig. Fig. 3 Insert the specified gauge between the top of the choke plate and the air horn wall

  1. Adjust by rotating the Allen screw in the center diaphragm housing.
  2.  
  3. Replace the vacuum hose.
  4.  

Throttle Position Transducer

This is only used on the 1978 vehicles with a manual transaxle.

  1. Disconnect the wire from the transducer.
  2.  
  3. Loosen the locknut.
  4.  
  5. Place a 21 / 32 in. (17mm) gauge between the outer portion of the transducer and the mounting bracket.
  6.  



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Fig. Fig. 4 Place the gauge between the outer portion of the transducer and the mounting bracket

  1. To adjust the gap, turn the transducer.
  2.  
  3. Tighten the locknut.
  4.  

Throttle Stop Speed

This applies to models without air conditioning.

  1. The engine should be fully warmed.
  2.  
  3. Put the transaxle in Neutral and set the parking brake.
  4.  
  5. Turn the headlights off.
  6.  
  7. Using a jumper wire, ground the idle stop carburetor switch.
  8.  



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Fig. Fig. 5 Adjusting the throttle stop speed

  1. Disconnect the idle stop solenoid wire.
  2.  
  3. Adjust the throttle stop speed screw to 700 rpm.
  4.  
  5. Reconnect the idle stop solenoid wire.
  6.  
  7. Disconnect the jumper wire from the carburetor switch.
  8.  

REMOVAL & INSTALLATION



Do not attempt to remove the carburetor from a hot engine that has just been run. Allow the engine to cool sufficiently. When removing the carburetor, it should not be necessary to disturb the intake manifold isolator mounting screws, unless you have determined that a leak exists in the isolator.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Remove the fuel filler cap to relieve pressure.
  6.  
  7. Disconnect the fuel inlet fitting, then catch any excess fuel that may flow out.
  8.  



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Fig. Fig. 6 With a rag at hand, disconnect all the fuel lines

  1. Tag and detach all electrical connections.
  2.  



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Fig. Fig. 7 Tag all the electrical leads to the carburetor, then disconnect them

  1. Disconnect the throttle linkage.
  2.  



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Fig. Fig. 8 Remove the clip on the throttle linkage



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Fig. Fig. 9 Use pliers to disengage the cable



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Fig. Fig. 10 The linkage will now slide out easily

  1. Disconnect and tag all air hoses.
  2.  
  3. Remove the carburetor mounting nuts, then the carburetor. Hold the carburetor level to avoid spilling fuel on a hot engine.
  4.  



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Fig. Fig. 11 Be sure all vacuum lines and wires are disconnected before removing the carburetor from the engine

  1. Installation is the reverse of removal. Be careful when installing the mounting nut nearest the fast idle lever. It is very easy to bend the lever. Tighten the mounting nuts evenly until snug to prevent vacuum leaks.
  2.  

Check to be sure the choke plate opens and closes fully and that full throttle travel is obtained.

OVERHAUL



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

Carburetor overhaul should be performed in a clean, dust-free area. Carefully disassemble the carburetor, keeping look-alike parts segregated. Note all jet sizes.

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

Blow out all passages and jets with compressed air and be sure there are no restrictions or blockages. Never use wire to clean jets, fuel passages or air bleeds.

Check all parts for wear or damage. If wear or damage is found, replace the complete assembly. Especially check the following:



Check the float and needle seat for wear. If any is found, replace the assembly.
 
Check the float hinge pin for wear and the floats for distortion or dents. Replace the float if fuel has leaked into it.
 
Check the throttle and choke shaft bores for out-of-round. Damage or wear to the throttle arm, shaft or shaft bore will often require replacement of the throttle body. These parts require close tolerances and an air leak here can cause poor starting and idling.
 
Inspect the idle mixture adjusting needles for burrs or grooves. Burrs or grooves will usually require replacement of the needles since a satisfactory idle cannot be obtained.
 
Test the accelerator pump check valves. They should pass air one way only. Test for proper seating by blowing and sucking on the valve. If the valve is satisfactory, wash the valve again to remove breath moisture.
 
Check the bowl cover for warping with a straightedge.
 
Closely inspect the valves and seats for wear or damage, replacing as necessary.
 
After the carburetor is assembled, check the choke valve for freedom of operation.
 

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

Some carburetor manufacturers supply overhaul kits of three types: minor repair, major repair and gasket kits. They basically consist of:

Minor Repair Kits:



All gaskets
 
Float needle valve
 
Volume control screw
 
All diaphragms
 
Pump diaphragm spring
 

Major Repair Kits:



All jets and gaskets
 
All diaphragms
 
Float needle valve
 
Volume control screw
 
Pump ball valve
 
Main jet carrier
 
Float
 
Complete intermediate rod
 
Intermediate pump lever
 
Complete injector tube
 
Assorted screws and washers Gasket Kits:
 
All gaskets
 

After cleaning and checking all components, reassemble the carburetor using new parts, using the exploded views in the car sections, if necessary. Make sure that all screws and jets are tight in their seats, but do not overtighten or the tips will be distorted. Do not tighten needle valves into their seats or uneven jetting will result. Always use new gaskets and adjust the float.

Disassembly
  1. Remove the fuel inlet fitting from the air horn.
  2.  

  1. Disconnect and remove the choke operating rod and seal.
  2.  

  1. Remove the solenoid retaining screws and the idle stop from the carburetor.
  2.  



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Fig. Fig. 12 Remove the fuel inlet fitting from the air horn



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Fig. Fig. 13 Disconnect and remove the choke operating rod and seal



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Fig. Fig. 14 Remove the solenoid retaining screws and the idle stop from the carburetor

  1. Loosen and remove the air horn mounting screws, then separate the air horn assembly from the carburetor body.
  2.  



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Fig. Fig. 15 Loosen and remove the air horn mounting screws, then separate the air horn assembly from the carburetor body

  1. Remove the float level pin, float and float inlet needle.
  2.  



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Fig. Fig. 16 Remove the float level pin, float and float inlet needle

  1. Separate the assembly from the air horn, remove the power valve diaphragm mounting screws.
  2.  



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Fig. Fig. 17 Remove the power valve diaphragm mounting screws

  1. A socket can be used to remove the needle and seat, also discard the gasket.
  2.  



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Fig. Fig. 18 A socket can be used to remove the needle and seat, also discard the gasket

  1. Remove the power valve.
  2.  



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Fig. Fig. 19 Remove the power valve

  1. Next remove the secondary main metering jet. Be sure to note the size so that it can be installed in its proper position.
  2.  



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Fig. Fig. 20 Next remove the secondary main metering jet. Be sure to note the size so that it can be installed in its proper position

  1. Take out the primary main metering jet. Be sure to note the size so that it can be installed in its proper position.
  2.  



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Fig. Fig. 21 Remove the primary main metering jet. Be sure to note the size so that it can be installed in its proper position

  1. Remove the secondary high speed bleed and secondary main well tube. Note the sizes for installation.
  2.  



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Fig. Fig. 22 Remove the secondary high speed bleed and secondary main well tube. Note the sizes for installation

  1. Remove the primary high speed bleed and primary main well tube. Note the sizes for installation
  2.  



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Fig. Fig. 23 Remove the primary high speed bleed and primary main well tube. Note the sizes for installation

  1. Remove the discharge nozzle screw, then the discharge nozzle and gasket.
  2.  
  3. Invert the carburetor and drop out the accelerator pump discharge weight ball and checkball. You will notice that both of the balls are the same size.
  4.  



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Fig. Fig. 24 Remove the discharge nozzle screw, then the nozzle and gasket

  1. Remove the upper choke diaphragm cover screws. Grind or file the head from the lower mounting screw, then remove the cover and spring.
  2.  



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Fig. Fig. 25 Remove the upper choke diaphragm cover screws

  1. Rotate the choke shaft diaphragm assembly clockwise, then remove from the housing. Remove end of lower screw from the housing. If the choke diaphragm is to be replaced, the diaphragm cover must also be replaced.
  2.  
  3. Remove the wide open cut-out switch mounting screws. Mark the location for assembly, then remove the harness mounting screws and open the retaining clip. Remove the wires from the connector, then thread through the clip.
  4.  



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Fig. Fig. 26 Remove the wide open cut-out switch mounting screws

  1. Remove the idle mixture screw.
  2.  
  3. Clean and inspect the carburetor, then reassemble. In the reverse of disassembly.
  4.  



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Fig. Fig. 27 The choke housing contains few parts, the diaphragm can go bad and should be checked and replaced if needed.



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Fig. Fig. 28 Holley 5220 with A/C-1979-80



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Fig. Fig. 29 Holley 5220 without A/C-1979-80



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Fig. Fig. 30 Holley 6520-1981-82



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Fig. Fig. 31 Holley 5220 with manual transaxle with A/C-1981-82



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Fig. Fig. 32 Holley 5220 with manual transaxle, without A/C-1981-82



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Fig. Fig. 33 Holley 5220-1983 and later



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Fig. Fig. 34 Holley 6520-1983 and later



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Fig. Fig. 35 Carburetor Specifications Holley 5220



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Fig. Fig. 36 Carburetor Specifications Holley 6520



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Fig. Fig. 37 Carburetor Specifications Holley 52206520

 
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