Adjusting a Holley 94 carburetor involves tuning various components such as the idle mixture screws, the idle speed screw, and the float level. Before you start making adjustments, make sure the engine is warm, and the choke is fully open. Here’s a step-by-step guide to help you with the adjustment process:
1. Idle Mixture Screws Adjustment:
- Locate the idle mixture screws on the metering block. There might be one or two, depending on the model.
- Turn the screws in (clockwise) gently until they lightly seat. Count the turns, so you have a reference.
- Now, turn the screws out (counter-clockwise) about 1 to 1.5 turns as a preliminary setting.
2. Idle Speed Screw Adjustment:
- Locate the idle speed screw on the throttle linkage.
- Start the engine and let it warm up to operating temperature.
- Adjust the idle speed screw to attain the desired idle RPM. The typical idle speed is about 700-800 RPM for manual transmission and 600-700 RPM for automatic transmission.
3. Accelerator Pump Adjustment (if necessary):
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If there’s a hesitation or stumble during acceleration, you may need to adjust the accelerator pump.
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Change the position of the pump linkage to a different hole to either increase or decrease the pump shot.

4. Recheck and Fine-Tuning:
- After making the adjustments, it’s essential to recheck the settings.
- Repeat the process if necessary, making fine adjustments to the idle mixture screws and idle speed screw until the engine runs smoothly at all speeds.
Safety Precautions:
- Always perform adjustments in a well-ventilated area to avoid the accumulation of exhaust fumes.
- Ensure the engine is off while making adjustments to avoid moving parts.
- Be cautious of hot engine components to avoid burns and injuries.
Adjusting a Holley 94 carburetor may require patience and multiple attempts to get the settings perfect. If you find difficulty in tuning the carburetor, it may be wise to consult with a professional mechanic or refer to the specific Holley 94 carburetor manual for more detailed instructions and specifications.