Choke Vacuum Kick

Fig. 7 Choke vacuum kick adjustment. 5220 carburetor:

Open throttle, close choke, then close throttle to trap fast idle system in closed choke position. Using an external vacuum source, apply 15 inches of vacuum to choke diaphragm. Apply closing pressure to position choke at smallest opening without distorting linkage. An internal spring will compress to a stop inside choke system. Insert specified gauge between upper edge of choke valve and air horn wall at primary throttle end of carburetor, Fig. 7. To adjust, rotate allen head screw in center of diaphragm housing.