How to Tune a Holley 2300

by Kelvin Hayes

Tuning a 2300 Holley Carburetor is a straightforward process thanks to Holley's simple design and exterior tuning capability, meaning the carburetor may be adjusted on the fly while mounted to the intake manifold. The Holley 2300 is a double barrel, manual choke carburetor with an air flow rating of 500 CFM (cubic feet per minute), designed for mounting on small block American engines of the 1960s and 1970s with square bore mounts.

Step 1

Place the vehicle on a flat surface.

Step 2

Remove the fuel bowl sight plug screw and evaluate the fuel level. Ensure that the fuel trickles out of the port hole.

Step 3

Turn the fuel bowl adjustment screw and nut up two turns. Start the engine and turn the adjustment nut clockwise with a wrench to lower the fuel level, or counterclockwise to raise the fuel level. Ensure that the adjustment screw is not turned during the "nut" adjustment. However, when the correct fuel level is reached, hold the nut stationary while tightening the screw.

Step 4

Reinsert the sight plug screw and tighten.

Step 5

Idle the engine and listen for a smooth idle. If the idle is rough, you'll need to adjust the idle mix screws until the maximum vacuum is reached.

Step 6

Attach a vacuum gauge to the vacuum check port on the intake manifold.

Step 7

Locate the mix adjustment screws on both sides of the metering block, between the fuel bowl and the center body of the carburetor. Tighten the screws, then back them out 1.5 turns.

Step 8

Adjust the mix screws in equal increments until their adjustment no longer renders an increase in the vacuum level of the intake. At this point, maximum vacuum is reached, and the idle mix is set properly.

Step 9

Check the throttle plates to ensure they're operating smoothly, with the engine off. Spray carburetor cleaner into the throttle bore in short bursts. Start the engine and operate the throttle body to ensure the engine is accelerating properly.

Step 10

Locate the throttle plate cam on the driver's side of the carburetor and adjust the cam pin higher or lower to retard or advance the throttle plate operation. This will tune the throttle plates to open correctly, allowing for smooth, crisp acceleration.

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