BBD Troubleshooting Pg2

Which Check Ball Goes in the Discharge?

On the solid fuel type of carburetor the smaller checkball resides in the main discharge. The bigger checkball resides at the bottom of the accelerator pump well.

Hard Starting After Sitting

The following are things you need to look at, not in any order:

  • The float bowl should be vented. Follow any vent hole on the bowl cover to make sure it is clear.
  • After turning off the engine look down the carburetor bore. If you see fuel dripping from the venturi then you have a leaking main discharge. The check ball may need to be seated (tap lightly to form a seal). Venturi gasket may not be sitting flat. They sometimes need to be trimmed.
  • Percolation – After turning off a hot engine, the gas can boil out of the carburetor. You would most likely get a strong gas smell just after turning off the engine.
  • Having the wrong gas cap can cause the gas to be siphoned. Putting a non vented cap when it requires a vented cap can be a problem.

Why Can’t I Get My Carburetor to Idle?

So you just can’t get the carb to idle down hot, or cold.

Top of the list is the throttle valves. They may have been inserted in the wrong direction.

It doesn’t take much of a bump to nick the throttle valves or knock them out of align­ment. If this happens, it will be impossible to get the two sides of the carburetor balanced or the engine idle smoothed out.

Carter BBD Throttle Valves


Updated on 04/17/2022

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