Carburetor Idle Adjustment

Noah and 5 other contributors

Last updated on April 18, 2018

15 minutes

Easy

Action Shots

Introduction

Go to step 1

In this guide, you will be instructed on how to adjust and synchronize the output of the two carburetors.

What you need

Parts

Tools

3/8" Wrench Available for sale on Home Depot
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Step 1 Carburetor Idle Adjustment

Carburetor Idle Adjustment, Carburetor Idle Adjustment: step 1, image 1 of 2

Carburetor Idle Adjustment, Carburetor Idle Adjustment: step 1, image 2 of 2

Use a 3/8 socket wrench to loosen the retaining bolts on the air cleaner.
Rotate the air cleaner so that the throats of both carburetors are clear. Now you will be able to adjust them.
Start the engine

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Step 2

Allow time for the engine to warm up completely
Attach carburetor synchronization tool to one of the carburetors
Observe the relative reading, and remember it.
This reading is a measurement of the airflow speed

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Step 3

Set the synchronization device on the other carburetor.
Using a Flathead screw-driver, twist the idle speed screw in to raise the flow, and out to lower it.
Recheck both carburetors and adjust as needed to get the flow as equal as possible.

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Step 4

Now, the idle mixture screws must be adjusted.
It is important that when the screws are adjusted they are adjusted the same amount in the same direction.
Turn both screws in, or out an 1/8 or a turn at a time until the fastest idle speed is achieved.
Before proceeding with this step you should have already checked your ignition timing, if you have not do it now, and then continue from here.

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Step 5

Finally, raise or lower the idle speed screws until the idle speed is about 550 RPM
Once more, it is important to adjust the screws the same amount.
Rotate the aircleaner back to its original position, and re-tighten the 3/8 nuts on the retainers

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Conclusion

Congratulations, your Corvair should now idle properly. If the Carburetors are still not operating properly, then the linkage is not synchronized, or they are in need of repair or rebuild. (A linkage adjustment and rebuild guide will be made soon!)

26 other people completed this guide.