Howdy,
You will find that the float, isn't. It is either waterlogged, or if a metal float, has a hole in it that has allowed it to fill with fuel. With the inlet needle not held closed by the float, the fuel just runs through, over fills the float chamber, and the excess runs out a drain all over the place. DO NOT PLUG. Repair properly by sevicing or replacement of the float. Clean the inlet orifices while you are at it. They are small holes in the tube that usually screws into the carb body in the center of the inlet chamber. Rod out the holes carefully, with out enlarging or reshaping them. In otherwise use a correct size smooth wire to clean. Clean the carb up generally with aerosol carb cleanner from a spray can that you get at the autoparts house.
These old carbs can be rebuilt easier than the modern ones, and will last about forever if the above is taken care of. Inlet needles will wear a groove in their tapered end that can prevent proper seal, or dirt and debris can get in there also preventing the needle from closing. These problems are less common, but should be checked for while you have it apart. Be sure not to loose the little clip wire that holds float lever to the inlet needle!
Regards,
Walt Galer
