Holley Model 6520 2 Barrel Carburetor

Fig. 4 Measuring float level:

Fig. 5 Adjusting float level:

FLOAT LEVEL
Invert air horn and insert specified gauge between float and air horn, Fig. 4. To adjust, use a small screwdriver to bend tang, Fig. 5.

Fig. 6 Measuring float drop:

Fig. 7 Adjusting float drop:

FLOAT DROP
Using a suitable depth gauge measure float drop, Fig. 6. To adjust, use a small screwdriver to bend tang, Fig. 7.

Fig. 8 Adjusting choke vacuum kick:

CHOKE VACUUM KICK
Open throttle and close choke valve, then close throttle to retain choke valve in the closed position. Disconnect vacuum hose from carburetor and connect an external vacuum source. Apply 15 inches Hg. of vacuum or more. Apply sufficient closing pressure to choke valve, using care not to distort linkage. Note that an internal spring will compress to a stop within the choke system Insert the specified gauge in center area between top of choke valve and air horn wall at primary throttle end of carburetor, Fig. 8. Adjust clearance by rotating the allen head screw in center of diaphragm housing.