Pull the needle out and see if there is the slightest suggestion of an indentation in the black part of the needle (pretty close to invisible, get a teenager to look). That is all it will take for the needle to not work correctly and overfill. If there is, buy spring loaded, Holley needle and seats. If there isn't take the bowl, with the float still inside, turn it over and make sure it is level or slightly lower. This will tell you if your float tab is correct.