If the float needle isn't sealing,.. it don't matter where you set the float,... gas will still enter...

Remove float bowl,.. and the fuel line from petcock... blow into the fuel line as you gently raise the float with your finger...
You should feel the air block off with the gentlest pressure of your finger at some point... if air still gets by,... you need a new needle and seat, or try cleaning the old one and test again...