My Autolite 1100 leaks down if you let it sit 15 min or so and it blows black smoke when you start the engine, it also surges at cruise speeds.
- The 1100 & 1101 can’t leak down through the main body like some carburetors can. Not knowing the condition of the carburetor (recent carb overhaul done correctly or not overhauled recently) there are several possibilities.
- One of the most common problems is the main discharge leaking gas. After driving, turn off the engine and look down the carburetor. If you see gas dribbling from the venturi then you have a leak. Try seating the check ball by tapping on it lightly. Is the check weight there?
- If it is the old rubber/nitrophyl float I would replace it with a brass float.
- Some carbs can percolate because of their environment. (Closed small engine compartments like vans). You can try a thicker flange gasket which acts as a thermal barrier to the carburetor as the engine overheats the carb on hot soak.
