Hey there. On those old Zenith carbs, adjusting the float is pretty straightforward. You'll need to pull the carb and drop the bowl. Then, flip the top half of the carb upside down, so the float's own weight gently closes the needle valve. The adjustment is made by carefully bending the little metal tab that contacts the needle. A good rule of thumb is to get the float to sit parallel with the carb body, which is usually around 1/4 inch from the gasket surface. While you have it apart, it's a really good idea to make sure the needle and its seat are clean and not worn. A worn-out needle will leak no matter how you set the float.
