How to Adjust an Electric Choke on an Edelbrock Carb
If you have an older car equipped with a carburetor, adjusting the electric choke is an important maintenance task. The electric choke controls the air/fuel mixture on cold startups, gradually opening to allow more air into the engine as it warms up. Without proper choke adjustment, you may experience stalling, rough idling, or even engine damage from running too rich or lean.
Adjusting the electric choke on an Edelbrock carburetor is straightforward when you know the basic steps. In this detailed guide, we’ll cover everything you need to get your choke dialed in perfectly. Proper choke adjustment takes some trial and error, so expect to spend a little time tuning it. Safety first – make sure the car is off and cool before working on any carburetor components. With some simple hand tools and patience, you’ll have your Edelbrock choke working like new.
Key Steps to Adjusting an Edelbrock Electric Choke:
- Identify the choke type
- Locate the choke housing
- Adjust the choke housing
- Adjust the choke spring
- Adjust the choke coil
- Adjust the fast idle cam
- Adjust the choke pull-off
- Reinstall choke housing
- Final adjustments and testing
These 9 steps encompass the entire electric choke adjustment process. Before getting started, let’s go over some choke adjustment basics and tips.
Choke Adjustment Tips:
- Adjust with a cool engine and car off
- Make adjustments in small increments
- Start the car after each adjustment to test
- Expect some trial and error dialing it in
- Consult your specific carb’s instructions
- Be patient – proper adjustment takes time
Adjusting your electric choke prevents cold start issues like stalling, surging, backfiring, and rough idle when your engine is cold. It can also improve drivability and fuel efficiency as the engine warms up. Taking the time to properly tune your choke will enhance performance and extend the life of your Edelbrock carb.
Identify the Type of Choke
Edelbrock carburetors feature two common electric choke types:
Coil Choke – Uses a bimetallic coil that closes the choke plate when cold. When energized, the coil heats up and opens the choke plate.
Stepper Motor Choke – An electric stepper motor controls the choke plate position electronically. This style requires wiring to an ignition switched 12V source.
Before adjusting, you need to identify the type of electric choke on your carburetor. Examine the choke housing on the top-front of the carb. The coil choke style has a small round cover. Stepper motor chokes have a square housing with two wires.
Consult your owner’s manual if you’re unsure of the choke type. The adjustment procedure differs slightly between the two. On coil chokes, you’ll adjust the choke cover, spring, and coil assembly. For stepper motors, you’re adjusting the linkage and choke pull-off only.
Once you’ve identified the choke type, gather any specialty tools required. You’ll need standard wrenches, screwdrivers, and pliers. A factory service manual is also handy for specs and troubleshooting.
Locate the Choke Housing
The choke housing is mounted on the forward top side of the carburetor. On an Edelbrock carb, you’ll see a circular or square choke cover housing attached to the air horn with two screws.
Before adjusting the choke, you’ll need to remove the housing assembly. This exposes the choke mechanism so you can tune it properly. Always let the engine cool completely before working on the carburetor.
Follow these steps to remove the choke housing:
- Disconnect the negative battery cable.
- Release the choke cover retainer clips or loosen the retaining screws.
- Detach any choke setting/bimetallic coils.
- Disconnect the choke pull-off rod if equipped.
- Remove the two choke cover housing screws.
- Carefully remove the choke cover and components.
Avoid bending or damaging any choke parts during removal. Lay the components out in order so you can reinstall them correctly. Many chokes contain delicate levers and springs that are critical for proper functioning.
With the choke housing removed, you can now begin the adjustment process. Consult your Edelbrock carburetor manual for model-specific details.
Adjust the Choke Housing
On Edelbrock carburetors with a bimetallic coil choke, adjusting the choke housing is first. This controls the choke plate angle during cold starts. You want a fully closed plate when cold, with gradual opening as the engine warms.
To adjust the choke housing:
- Examine the choke plate operation with the engine off and cold. Actuate the choke by hand while observing plate movement.
- Adjust the choke cover alignment until the choke plate seals completely when closed. Loosen the mounting screws and rotate the housing slightly if needed.
- Tighten the mounting screws and recheck alignment. Actuate the choke to confirm full closure.
- Start the engine and let it warm up, ensuring the choke plate opens fully.
- Adjust the cover alignment again if needed until you achieve complete cold closure and open operation.
Adjustments are very small – a few degrees of housing rotation at most. Be patient and allow the engine to cool between adjustments. The goal is smooth choke operation from fully closed to fully open.
Adjust the Choke Spring
The tension of the choke spring controls how quickly the choke plate opens when energized. You want a smooth, gradual opening without sticking.
To adjust the choke spring:
- Locate the choke spring attached to the choke lever.
- With the engine cold, disconnect the choke rod or coil electrical connector.
- Remove the screw holding the choke spring.
- To increase tension, tighten the spring one coil at a time. Loosen to reduce tension.
- Reattach the spring and reconnect the rod or electrical connector.
- Start the engine and let it warm fully, ensuring the choke opens gradually.
- Repeat adjustments until the choke plate motion is smooth from closed to open.
Too much spring tension can damage the choke mechanism. Make small 1/4 turn adjustments and test after each change. The spring should hold the plate closed when cold but allow it to open once the engine warms.
Adjust the Choke Coil
Coil chokes use a bimetallic spring coil wound into a housing. When energized, the coil heats up and unwinds, opening the choke plate via the linkage. The coil requires precise adjustment for proper choke operation.
To adjust the choke coil:
- Examine the bimetallic coil housing, locating the movable disc.
- With the engine completely cold, turn the disc to increase coil tension until the choke plate just closes completely.
- Start the engine and let it fully warm up, making sure the choke plate opens all the way.
- If needed, adjust the movable disc again to fine-tune the cold choke closure.
- Allow the engine to cool and confirm the choke closes completely when cold.
Avoid over-tightening the coil disc, as too much tension can damage the spring. Adjust in small increments and test thoroughly after each change. Proper adjustment prevents choke sticking and ensures smooth operation.
Adjust the Fast Idle Cam
The fast idle cam holds the throttle open slightly when the choke is engaged. This prevents cold stalling. Adjusting the cam ensures fast idle engagement only when the engine is cold.
To adjust the fast idle cam:
- Locate the fast idle cam attached to choke linkage.
- Loosen the cam set screw or retaining nut.
- Adjust cam position so it only contacts and opens the throttle when choke is fully closed.
- Tighten the retaining fastener and recheck adjustment.
- Start engine and confirm fast idle only engages with a cold, closed choke. Readjust as needed.
You want minimal fast idle speed, just enough to prevent stalling. Too much fast idle can make the engine difficult to control when cold. Adjust the cam in small increments until fast idle engagement is minimal but effective.
Adjust the Choke Pull-Off
The choke pull-off automatically begins opening the choke once the engine reaches operating temperature. It prevents choke sticking when warmed up.
To adjust the choke pull-off:
- Locate the choke pull-off rod, spring, and bracket assembly.
- Loosen the locknut on the assembly.
- Turn the adjuster nut in or out to set pull-off travel distance.
- Tighten the locknut once set.
- Start engine and confirm the choke fully opens once warmed up.
- Readjust as needed until the pull-off reliably opens the warm choke.
Insufficient pull-off travel can lead to choke sticking and black smoke once warmed up. Adjust pull-off travel gradually until the choke plate opens fully when hot. Avoid over-tightening the assembly.
Reinstall Choke Housing
Once all adjustments are complete, you can reinstall the choke cover housing onto the carburetor. Reverse the removal steps, taking care not to bend or damage any choke components.
Follow this process to reinstall the choke housing:
- Position the choke plate lever and actuating rod correctly.
- Attach any coils, springs, and clips in their original positions.
- Install the two choke housing retaining screws loosely.
- Align the housing until the choke plate seals fully.
- Tighten the housing screws once aligned properly.
- Reconnect the negative battery cable.
With the choke cover reinstalled, all adjustments are complete. Starting the engine and allowing it to warm up fully is the best test. Carefully inspect choke function, fast idle engagement, and pull-off activation as it warms.
Final Adjustments and Testing
Tuning the electric choke requires a careful, methodical process with several rounds of adjustment. Expect to fine-tune your adjustments several times to get it perfect.
Follow this process for final dialing and testing:
- Make several cold start tests, listening for smooth operation and clean starts.
- Confirm the choke plate seals completely when cold.
- Check that fast idle engages only when necessary.
- Allow engine to reach full operating temperature until choke fully opens.
- Adjust any sticking, surging, or rough operation by tweaking the spring, coil, pull-off, and linkage as needed.
- Let engine cool fully between adjustments to test choke closure.
- Take your time and make changes in small increments.
- Consult the manufacturer’s specs and operating temperatures if needed.
- Confirm normal operation at both cold start and full operating temperature.
Proper choke adjustment prevents cold start issues like flooding, stalling, and hesitation. It also improves drivability and fuel efficiency as the engine warms up. Symptoms of incorrect choke adjustment include:
- Hard starting when cold.
- Rough idle or stalling on cold startups.
- Sputtering, surging, or backfiring as engine warms.
- Black smoke or choke sticking when hot.
Carefully tuning your electric choke results in easy cold starts, smooth operation on warmup, and optimal performance. Your Edelbrock carb will run its best following a methodical adjustment process.
Maintaining your Electric Choke
Once adjusted properly, minimal maintenance is required on electric chokes. Here are some tips for keeping your choke working correctly:
- Periodically check adjustment and actuation to confirm proper operation.
- Lubricate the choke shaft and linkage with light oil as needed to prevent sticking.
- Keep linkage and coils free of dirt buildup.
- Check choke pull-off and springs for wear or fatigue.
- Test heating element coils for oxidation or damage.
- Verify wiring to stepper motors for corrosion and loose connections.
- Consult your service manual for recommended choke maintenance intervals.
Taking the time to properly tune your electric choke results in a smooth running engine. Adjustment prevents cold start issues and stalling. Follow the steps outlined in this guide to dial-in perfect choke function. Your Edelbrock carburetor will deliver reliable performance for years to come.
