How to Tune a Demon Carbby Cecil Fontaine
Demon carburetors offer several options to adjust the engine´s performance. This can be done by adjusting the carb's performance screws (idle-mixture screws and float-bowl screws) and butterfly positions. There are two important signs which indicate that the carburetor needs to be tuned: if the engine runs rough and rich when idling or it emits black exhaust smoke. If you notice these symptoms, tune your Demon carb in your garage for improved engine performance.
Turn your car on and let it run for 10 minutes to allow the engine to reach its operating temperature. After 10 minutes, lift the hood and locate your Demon carb.
Adjust the four idle-mixture screws on the corners of the carb. Use a screwdriver to tighten the screws and then loosen each of them by one-half turn.
Locate the three float-bowl screws. One screw is below the glass in the middle of the bowl and the other two are on the secondary side of the bowl. Tighten the screws and then loosen them a half-turn, as you did in the previous step.
Adjust your carb's butterfly positions --- the two valves on either side of the carb. Open the valves until you hear the engine running smoothly. Turn the car off and close the hood.
Things You'll Need
Based in Colorado, Cecil Fontaine has been writing and editing since 2009, specializing in Brazilian travel guides. He received his Bachelor of Arts in political economy from the University of California, Berkeley in 2008.