How To Adjust the Idle on a Carbureted Car

A car's engine performance can be affected if there are certain incorrect settings in the carburetor. You will know if this there is a problem when the engine either runs extremely fast or really slow. Once you notice this in your car, then adjusting the carburetor idle may be necessary. Here's how:

  1. Car manual. Have the car owner's manual for reference on carburetor idle specifications. Refer to your car owner's manual for the manufacturer recommended carburetor idle specifications.
  2. Secure hand brake and tires. For safety measure, set the hand brake and have the tires securely blocked. Better yet, have someone assist you and let him sit inside the car.
  3. Turn on the car. The first thing you will need to do is to switch on the engine while the car hood is securely opened. Leave the engine running to get to its usual running temperature.
  4. Get to the car's carburetor. Once the car has reached it usual running temperature, then you can switch the engine off. Now, you will need to go under the car hood to get to the carburetor. Some cars may have the carburetor under the air filter setup. If so, then simply take this out to get to the carburetor.
  5. Adjust the settings. Adjust the carburetor's settings based on the car manufacturer's recommendations. Look for the screw used to adjust the idle settings of the carburetor. It should be found at the side of the carburetor, right beneath the fast idle cam. Now, turning the idle adjustment screw clockwise will increase the idle speed of the carburetor while unscrewing it will in turn result in a decreased carburetor idle speed. Now, get the car's engine going again. Go to the carburetor once more and turn the screw clockwise for just one half turn using a flat tip screwdriver if you want to increase the idle speed. Turn it counter clockwise if you want to lower the idle speed on the other hand. Bear in mind that you will have to do this while the car's engine is running steadily.
  6. Check the tachometer. Now, check the tachometer on the dashboard to see if the RPM reading for the carburetor idle is correct. Simply screw or unscrew the idle adjustment screw once more to achieve the correct RPM setting.

Once done, all you need to do is to put the air filter setup back into its usual place and close the hood of your car.


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