GAS CARBURETORS

1. How much fuel pressure does my C&S gas carburetor require?

   In most cases, C&S gas carburetors are calibrated to use 7-8 PSI constant pressure.

2. How big a carburetor do I need for my engine on gas?

   For circle track, C&S recommends a carburetor that will guarantee .8 to 1 inch of mercury at the horsepower peak. For drag racing, C&S recommends somewhere in the .2 - .6 range, depending on application. The correct CFM rating can be obtained by multiplying the horsepower peak X 1.3. This gives you CFM required.

3. My car is hesitating coming off the turn. What do I check?

   Three common possibilities:

   • Base adjustment. (To obtain a correct base adjustment, refer to Preliminary Tuning of a New Racing Carburetor.)
   • In some cases, too high-octane fuel.
   • Heat range on spark plugs.

4. How do I determine proper jetting?

   C&S recommends main jet tuning of your carburetor with our part number 70194-1 Rich/Lean Indicator. That is the best method. Spark plug color can be used as an air fuel reference, but provided today’s complex racing fuels and the additives they contain, this can sometimes prove difficult.

5. I’m running two different motors, a 355-inch small block and a 406-cubic-inch small block. Do you have a carburetor that will work best on both of these?

   In most cases, the smaller carburetor that will be sized for the 355 engines will work on the 406 with a little loss to top-end performance. But a carburetor that is sized for a 406 may not run satisfactorily on restarts or low speed. When choosing a carburetor with these two combinations, it is best to choose the carburetor for the smaller engine. We recommend buying the properly sized carburetor for each engine.

6. How much ignition power do I need for my engine?

   Typically, any engine up to 11:1 compression requires an ignition system that will supply 105 to 115 millijoules spark energy. The higher the compression, the more millijoules are required. Remember you can never have TOO MUCH ignition system. A simple test would be to decrease plug gap or go to a fine wire plug. Any gain in performance shows the lack of ignition power. Remember, one of the key components is a good set of spark plug wires.

7. I race a dry slick track and limited tire rule. What can I do to improve drive-ability?

   Three things that help: C&S Dry Slick Link (part number 1902-CS) coupled with a lot of throttle pedal travel, at least 3-4 inches, or in extreme cases a vacuum secondary carburetor can be beneficial (part number 054800VS).

8. What can I do to make my engine run cooler?

   We have a 25% methanol carburetor specification and a blending agent that is mandatory to use with gas/alcohol blends. (Part number 4701 qt. 4705 gal.) One quart will blend 32 gallons of fuel. Another benefit of a 25% methanol blend is that most engines will produce about 2% - 4% more power.