These Quick Fuel QFX-Series carburetors feature an all-new die-cast aluminum main body, which has a lengthened venturi section for greater midrange torque and better airflow. The annular booster venturis are precision die-cast with CNC-machined billet aluminum inserts, providing smoother and more refined air entry, a stronger vacuum signal, less turbulence, and improved fuel emulsion for better combustion. The Quick Fuel QFX-Series carburetors use red anodized billet aluminum CNC-machined metering blocks featuring 3-circuit metering (gasoline carburetors), changeable emulsion, idle feed, and intermediate bowl and feed discharge. Next, the die-cast aluminum fuel bowl combines high strength with significant weight reduction. They feature dual threaded fuel inlets and outlets and dual sight glass holes to easily set the float levels. The Quick Fuel QFX-Series carburetors feature Quick Fuel's external linkage with four different links to select the amount of primary throttle opening before the secondaries open: moderate progressive (25 percent), medium progressive (40 percent), full progressive (50 percent), and 1:1.