Edelbrock manufactures two types of carburetors: the Performer Series and the AVS Thunder Series. Each series can be tuned the same way. Ensuring that the carburetor is properly tuned is quite simple, and can ensure that the engine runs properly. Turning the carburetor can also increase mileage.
Setting the Idle Mixture
Properly setting the air/fuel mixture at idle is the most important aspect of tuning. If the air/fuel mixture is too lean -- the mixture has too much air -- the engine can either miss or surge, bogging down acceleration and causing pre-ignition detonation. A mixture that's too rich -- too much fuel -- can cause the engine to stumble and dramatically reduces fuel efficiency.
To set the mixture, first ensure that the engine is warm and the air cleaner assembly is in place. Locate the two idle mixture screws on the front of the carburetor. While the engine is running, slowly turn either screw in either direction until the engine speed increases to its maximum point on its own. Turn the remaining screw until the engine again reaches its maximum speed. If the engine's idle speed is too high after the adjustments have been made, reduce the idle speed by turning the idle speed screw counterclockwise until the engine reaches the desired engine speed. The idle speed screw is located on the driver's side of the carburetor.
Adjusting the Float
Edelbrock carburetors use two floats. If either float is not adjusted properly, meaning that the float hangs either too low or too high, the engine can stumble upon acceleration or stall upon hard braking. The carburetor can also flood and fuel economy can suffer.
To adjust the floats, first remove the carburetor's air horn. The air horn is the top of the carburetor, sometimes referred to as the carburetor's "cover." Several screws hold the air horn in place. Remove the screws with a screwdriver, then lift the air horn off of the carburetor. Turn the air horn upside down to expose the two floats. Note that each float attaches to the underside of the air horn with a hinge. The distance between the free end of the float and the bottom of the air horn must be 7/16 inch. To adjust the distance, bend the tab at the back of the float where the float meets the hinge. This initial adjustment is necessary to properly adjust the floats when they hang down. Turn the air horn over so that the floats hang down. The distance between the top of the free end of the float to the bottom of the air horn must be 15/16 inch. To adjust the distance, bend the tab on the float where the float meets the hinge. Install the air horn back onto the top of the carburetor to complete the process.
- Edelbrock Performer Series and Thunder Series AVS Carburetor Owner's Manual; Edelbrock Corporation; 2005
- How to Rebuild and Modify Carter/Edelbrock Carburetors: Performance, Street, and Off-Road Applications; Dave Emanuel; 2007
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