Here are some things you can look at, not in any order.
- When using an electric fuel pump be sure you have a regulator between the pump and the carburetor. Electric fuel pumps put out more pressure than your carburetor can handle. Set the regulator to 4 lbs.
- If you have a standard fuel pump test the pressure. New fuel pumps are especially suspect.
- Test the needle & seat. This is the most likely cause. Dirt may have gotten into the seat and happens more than you would think. Rebuild the carburetor, put it back on the car and crud from the gas tank gets into the carburetor. Fuel filters will not stop everything. Try blowing air into the inlet. That might dislodge any dirt that is in the needle and seat, or float valve.
- Test the float for leaks. Shake the float to see if there is fuel inside. If it has been sitting for months then the gas inside the float may have evaporated. Heat up a pan of water just prior to boiling and immerse the float. Any bubbles indicate a leak.
- Move the float up and down by hand to see if it is catching. It could be the float pin is worn.
Gas Runs Out Of The Mounting Gasket After Turning the Engine Off
Basically gas is running down from the top to the throttle valves, then leaks out the shaft, or gasket.
- Percolation, or heat soak. Engine gets hot and then turning off the engine, the gas boils.
- Try using different gas.
- Make sure the engine isn’t running over normal.
- Fuel line too close to the exhaust manifold.
- Anti Percolator Adjustment
- Crack throttle valve .030″ between throttle valve and bore of carburetor, side opposite idle port. Adjust by bending rocker arm.
- After turning off the engine look down the bore. If gas is dribbling into the bore then the main discharge may be leaking. If it is then tap on the check ball lightly to form a good seat.