How to Fine-Tune Edelbrock Carburetors
Edelbrock carburetors can be found on thousands of classic and restored engines around the world. Known as a family of devoted performance junkies, the Edelbrock Performer carburetors are the most popular version. Delivering the correct amount of fuel and air into the engine is necessary for smooth driving, so tuning the carburetor to the engine is important for the best performance. When it comes time to tune an Edelbrock family carburetor, you'll need some simple tools and trial and error to get the perfect mix of fuel and air into the combustion chambers of an equipped Edelbrock Performer carburetor.
- Difficulty:
- Moderate
Instructions
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1
Run the engine until the average operating temperature has been reached.
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2
Place the transmission in park on a level, flat surface that is well lighted and ventilated during the tuning of the carburetor.
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3
Open the hood to access the engine, and remove the air filter and cover by loosening the wing nut that secures the air filter and housing to the top of the carburetor.
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4
Inspect the carburetor to make sure the choke is completely open. This is when the carburetor's butterfly valves are open. These valves can restrict the amount of air into the carburetor during start-up, causing a fuel-rich mixture that is easier to ignite. Closed valves mean the choke is closed.
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5
Connect a tachometer gauge to the negative side of the ignition coil and to a good ground to show the RPMs the engine is building to before shifting or during acceleration.
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6
Connect a vacuum gauge to the vacuum lines going into the intake manifold with a T-adapter.
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7
Start the engine and locate two screws on the front of the carburetor that can be adjusted in or out. The adjustment alters the amount of fuel going into the engine at idle, and can be set for a richer or leaner burn condition.
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8
Set the idle to burn on a most lean condition without causing the engine to sputter, allowing for the highest amount of vacuum pressure to be built up before the activation of the accelerator pump.
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9
Set the screws to produce the highest amount of vacuum at idle. An engine should turn around 900 RPM; set the idle so that it makes the most vacuum pressure and idles smoothly within 100 RPM of the 900 RPM standard.
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10
Adjust the metering jets with a screwdriver so the carburetor injects enough fuel to create equal vacuum pressures during use.
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11
Press the accelerator hard enough to rev the engine up to 6,000 RPM, and watch the pressure of the vacuum as the tachometer needle goes up through the RPM levels. If a change in the pressure is noticed, an adjustment in fuel delivery is needed to eliminate this condition. The carburetor should deliver enough fuel without causing a lag in response or a sputtering from lack of fuel.
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12
Remove the tachometer and vacuum gauge from the engine compartment, and reconnect the vacuum hose to the intake manifold. Replace the air filter and housing to the top of the carburetor inlet, and secure with the wing nut fastener.
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13
Close the hood and go for a test drive. The engine should respond crisply when the accelerator is depressed and never lag under pressure from the driver after taking the correct steps to tune the carburetor to the engine properly.
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1
Tips & Warnings
Use carburetor cleaner to remove any debris from the carburetor linkage or body.
Place a rag or plug into the top of the carburetor to prevent debris from falling into the intake manifold.
Having the proper fuel mixture at each step of the fuel delivery will improve the response the engine gives during operation. All three stages of the carburetor must be tuned to get the best performance.
Gasoline and carburetor cleaner can ignite easily. Never work around open flames or smoke while tuning an Edelbrock carburetor.
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