How to Tune Weber Carburetors

by Robert Raphael

The carburetor of a car is the location where the gasoline that is vaporized in the engine is combined with air to create the explosion inherent in the combustion engine, which causes to the car to move. The precision of the carburetor controls is what affects the performance of your car, and this can be adjusted through a tuning procedure. Weber carburetors have easy-to-adjust tuning controls to allow you to perfect your driving experience without any special tools or experience.

Turn on the car to start the engine, and pop the hood of the car so you can access the carburetor.

Tighten the idle mixture screw until you hear the engine being to die down or weaken. The mixture screw is the one located on the carburetor, on the lower right side.

Loosen the mixture screw until you hear the engine running at its proper speed, and make one additional half turn of the screwdriver after hearing the good sound. This turn will make the engine sound worse again.

Retighten the screw until the engine sounds its healthiest and most robust. You can loosen it slightly if you overshoot the healthiest sound.

Move to the idle speed screw, which is located up and to the left of the mixture screw. Tighten this screw by half a turn and stop.

Make one-quarter-turn adjustments to the idle speed screw until your engine achieves between 900 and 1000 RPM. Whichever speed feels best on your car is the right one for you.

Check the idle mixture screw again once you have set the speed screw. Follow the same procedure as before until the engine sounds as fast and strong as possible.


  • check Tune your carburetor every time your car is serviced or has a part replaced to keep it at peak performance.


  • close Do not remove the screws completely or you will damage your car and carburetor.

Items you will need

About the Author

Based in New Jersey, Robert Raphael has been writing health and technology articles since 1993. His work has appeared in “Natural Living” magazine and “Extreme PC” magazine. Raphael received the Jonathan Melman Literary Award in 1994. He holds a Bachelor of Arts in journalism from Brandeis University.

Photo Credits

  • photo_camera american v8 engine image by kenmo from