Summit Racing | Carburetor Choke Tuning

Fuel-Rich Mix

Got an older car? Summit Racing has a large selection of carburetors, chokes and choke kits.

In this Summit Racing Quick Flick, Norm covers the basics of how to start a carbureted vehicle on a cold morning with either a manual choke or electronic choke. Learn the differences between an electronic and manual choke and how to properly find the right choke position.

Carburetor Electric & Manual Choke Tuning – Summit Racing Quick Flicks

What is a choke anyways?

When an engine is cold, it requires a richer air/fuel mixture to get started. A choke is used to create that fuel-rich mixture. The choke is a plate or blade that covers the primary barrels. It restricts airflow through the carburetor. This means that there is more fuel and less air entering the intake manifold. As the engine warms up, it is able to run on a leaner air/fuel mixture. The choke plate must be opened gradually to allow more air into the engine. Carburetors are available with or without a choke. There are also several types of chokes to choose from.

How is it operated?

Manually: A manual choke is controlled by a lever on the side of the carb. A lever or knob inside the vehicle is then attached by a cable. This requires a person inside the car to slowly open the choke by hand.

Automatically: An automatic choke uses a metal spring to open and close the choke plate. The spring is wound in a housing and attached to the choke linkage on one end. As the engine warms up, it warms the metal spring. As the spring warms, it expands, rotates, and opens the choke plate.

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