Edelbrock Carburetor Troubleshootingby John Stevens J.D.
Edelbrock carburetors are carefully tuned at the factory to work with the vast majority of applications. However, the carburetor can develop problems over time, usually due to a defective gasket or a component which has fallen out of adjustment. The hardest part of fixing a problem with an Edelbrock carburetor usually is determining what the problem is, although there are a few common ones identified by what the carburetor or engine is doing.
When the carburetor contains too much gasoline, it is said to be "flooded." Flooding is often accompanied with gasoline spilling out of the carburetor, and sometimes caused by a dirty fuel filter or an improper float level. Edelbrock carburetors use two floats, both of which are located on the underside of the airhorn. There must be a distance of 7/16 inch between the top of the outer edge of each float at the air horn gasket. To adjust the float, bend the tab at the back of the float. On occasion, dirt or metal may be clogging the needles and seats. To clear the clog, lightly tap on the fuel inlet fitting on the passenger's side of the carburetor with the handle of a screwdriver or wrench. The carburetor will also flood if the fuel pressure is too high. This is a common problem if the stock fuel pump has been replaced with a high performance fuel pump. A fuel pressure regulator should solve the problem.
Engine Idles Roughly
An idle problem is typically caused by an air leak at the carburetor's base gasket. The base gasket is located between the base of the carburetor and the intake manifold. To check for leaks, turn the engine on and lightly spray water around the base of the carburetor with a spray bottle. The water will seal the leak for a second or two and the speed of the engine will increase. If the gasket leaks, it must be replaced. The problem can also be due to an air/fuel mixture which is either too lean, meaning not enough fuel, or too rich, meaning not enough air. Remember to adjust the air/fuel mixture only after the engine has reached normal operating temperature. Before any adjustment is made to the carburetor, the ignition system, specifically the engine's timing, should be checked, because the ignition system is more often than not responsible for a poor idle.
Poor Fuel Economy
Poor fuel economy, like a rough idle, is commonly caused by a defective carburetor base gasket or a problem with the ignition system. Poor fuel economy can also result if either of the two floats are not adjusted properly, or if the air/fuel mixture is too lean or too rich. As with a flooding problem, the needle and seats may be clogged with dirt or metal, or the fuel pressure may be too high. The air horn gasket should also be checked for defects, which will allow air to leak from the carburetor.
- Edelbrock Performer Series & Thunder Series AVS Carburetor Owner's Manual; Edelbrock Corp.; 2005