How to Troubleshoot a Holley Carburetor
The Holley carburetor, made for vehicles during the 1950s (and used in many muscle cars of that era), is a device that mixes outside air with fuel from the vehicle's gasoline and reservoir tanks. The components work on the principles of vacuum pressure. The original Holley carburetor was a very reliable component. In 1968, Holley was purchased by Colt industries. The quality of the carburetors has since declined somewhat due to the use of cheaper materials in an attempt to cut costs.
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Instructions
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Check for corrosion on the throttle body portion of the carburetor by removing the air filter and looking down into the carburetor. To remove the filter, unscrew the center screw on the filter with a screwdriver and pull the air filter off the top of the carburetor. Then, look down into the carburetor. The Holley carburetor is partially made of zinc. This design, unfortunately, lends itself to corrosion if water is in the fuel (from condensation in the fuel tank). If you see corrosion, have the carburetor serviced and the rust removed immediately.
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Start the engine and listen for a rough idle or hesitation. The Holley carburetor's squirter check-needle seats sometimes are not pressed in far enough by the factory (or by a rebuild shop). This occasional problem needs to be serviced by a machine shop or a qualified mechanic, who can re-seat the check-needle seats for you.
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Check for engine hesitation or stalling. This is commonly caused by the economizer jet on the Holley carburetor being partially blocked with contaminants in the fuel. This happens primarily as a result of the fuel filter being clogged and foreign contaminates blowing by the filter element. It can also happen if contaminants are in the fuel tank (such as rust due to moisture or condensation inside the tank). Have this serviced by a professional mechanic.
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