Like possum said it's always nice to get specific information and even a picture, if possible, to help us better help you.
The first thing that comes to mind would be that your needle valve is not sealing properly or the float is sunk. Either way this will cause the fuel to continue to flow from the tank and usually into the crankcase so make sure to check your oil level before starting your engine or you could do major damage. If the oil is over-full you must change the oil before using the engine. Fix the carburetor problem first because if you don't it would be a waste of an oil change.
That is the float bowl vent, which leads me to advise you to follow lawnRangers post and replace the float needle and check to see if the float has a hole in it.
From your serial number you were included in the carbs that had the faulty plating on the needle valve leading to the needle valve corroding and either sticking open, like in your case, or sticking shut. Depending where you are located, the repair kit, or needle valve may not be available, and will have to replace the entire carb. My Kohler distributor doesn't carry any of the parts, except the complete carb.