Gas is Dribbling From Main Discharge at Idle

1. Discharge check ball is leaking. 

• Tap the check ball gently to form a good seal. Make sure the bigger check ball is inserted along with the check weight above it. See #36, #37.
  

1. Float Level Set Too High:

• If the float level inside the carburetor is set too high, it can cause excess fuel to enter the bowl, leading to fuel overflowing and dribbling out of the main discharge nozzle. Adjusting the float level to the correct specification can resolve this issue.
  

2. Needle and Seat Issues:

• The needle and seat regulate the flow of fuel into the carburetor bowl. If the needle or seat is worn, dirty, or not seating properly, it can allow too much fuel to enter, causing it to dribble out of the main discharge. Inspecting, cleaning, or replacing the needle and seat may be necessary.

3. Fuel Pressure Too High:

• Excessive fuel pressure can overwhelm the needle and seat, causing fuel to overflow into the carburetor. Ensuring that the fuel pressure is within the manufacturer's recommended range is important to prevent this issue.

4. Leaking or Damaged Float:

• A float that is leaking or damaged can become saturated with fuel and lose its buoyancy, causing it to sink and allow too much fuel into the bowl. Replacing a faulty float can solve this problem.

5. Clogged or Restricted Fuel Passages:

• Clogged fuel passages can create an imbalance in fuel distribution, leading to fuel dribbling from the main discharge. Cleaning the carburetor thoroughly to remove any blockages can help restore normal operation.

6. Vent Blockage:

• If the vent in the carburetor is blocked, it can cause pressure to build up, forcing fuel out of the main discharge nozzle. Ensuring the vent is clear can prevent this from happening.

7. Non Vented Gas Cap Installed

Addressing these potential causes through inspection, cleaning, and adjustment should help resolve the issue of fuel dribbling from the main discharge in your Holley 1940 carburetor.