How to Adjust a Holley Carb
Adjusting a Holley carburetor is a job that can be done in just a few minutes. Occasionally, the adjustment screws on a Holley carburetor will loosen from engine vibration while it is running, causing the motor to run poorly and reducing your fuel mileage. A poor running engine can also cause engine parts to fail quicker. You can adjust the Holley carburetor yourself, saving you the time and money of having a mechanic or someone else do the work for you.
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Instructions
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1
Locate the two idle mixture screws on both sides of the Holley carburetor metering block between the body of the carburetor and the float bowl on the side.
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2
Turn the adjustment screws gently with a screwdriver while the engine is off, turning the screws counter-clockwise until they bottom out. Turn the screws until you feel just a slight resistance to keep from over-tightening them.
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3
Rotate both screws clockwise 1-1/4 turns with a screwdriver to begin the idle adjustment. Turn the motor on and let it warm up for about five minutes.
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4
Pull the vacuum hose off the vacuum port at the bottom of the carburetor and attach a vacuum gauge to the vacuum port.
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5
Turn the idle adjustment screws on the Holley carburetor 1/4-turn clockwise at a time until the RPMs on the vacuum gauge reach 600 for both adjustment screws.
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6
Remove the vacuum gauge from the vacuum port and reattach the hose to the port. Shut the engine off.
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Tips & Warnings
Carefully turn the screws, when setting the adjustment screws, to prevent snapping them off from over-tightening.
References
Resources
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Comments
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I do not believe this is correct. You turn the screws CLOCKWISE to bottom them out. Turn counter-clockwise 1 1/2 turns as a base adjustment. Start the car and turn the screws out a half turn for each at a time until you get the best idle. Then turn clockwise until it starts to run rough. Then back out 1/2 turn.
