How to Modify a Carburetor

Adjusting Air and Fuel Mixture

1). Make sure the car is not running, and open the hood.
2). Unscrew the wing nut on top of the air filter.
3). Remove the air filter. The carburetor sits underneath the air filter.
4). Turn the screws on the lower-front section of your carburetor to the right with a flat-head screwdriver. Turn until the screws are tight. You tighten the screws all the way to have a starting point. The screws loosen themselves over time.
5). Slowly loosen each screw, one at a time. Turn each screw approximately two turns. Tightening the all the way and then loosening them two turns sets them back to the best position.

1). Start the engine, and let it warm up 15 to 20 minutes.
2). Turn the engine off.
3). Remove the wing nut from the top of the air filter. Then remove the air filter.
4). Remove the air filter base by lifting it off the carburetor.
5). Look for a screw under the fast idle cam. The screw is attached to the throttle cable on a spring-loaded hinge. This is the idle adjustment screw.
6). Start the car again.
7). Tighten the idle adjustment screw one-half turn clockwise with the screwdriver. Doing this increases the idle speed and is useful if the car idles roughly.
8). Let the car idle for 30 seconds before making any further adjustments.
9). Adjust the screw so that your car's idle speed is where you want it. If it is idling too fast, turn the screw counterclockwise. If the car is idling too slow, turn the screw clockwise again. Let the car idle for 30 seconds between adjustments.