To set the floats, loosen the slotted lock screw at the top of the fuel bowl, and then turn the large adjustment nut (which actually moves the needle-and-seat assembly up and down). Retighten the lock screw once the adjustment has been finalized. Keep an eye on the sight plughole. Remember, the fuel shouldn't pour out. Several companies offer clear sight plugs that allow you to see the float level without actually removing the plug. That can be a bonus, since raw fuel won't pour onto a hot intake manifold.