Turn the carburetor upside down and set the bottom of the float parallel to the mating surface of the carburetor body. Then turn the carburetor body right side up and set the lower face of the float as specified for your engine. I believe the drop measure is one inch +/- 1/8 inch from the mating surface to the bottom edge of the float.
If adjustment is needed be careful not to put pressure on the needle, which could damage the tip. Also be sure to install the spring clip from the needle to the float arm.
There is a small tab just off the hinge on the float arm. If the tab is set wrong, the float may not drop properly, which is the reason to check the drop.
