Choke Vacuum Kick

Fig. 8 Choke vacuum kick adjustment:

The choke diaphragm adjustment controls the fuel delivery while the engine is running. It positions the choke valve within the air horn by action of the linkage between choke shaft and diaphragm. The diaphragm must be energized to measure the vacuum kick adjustment. Use either a distributor test machine with a vacuum source, or vacuum supplied by another vehicle.
1. Open throttle and close choke, then close throttle to place fast idle cam at closed choke position.
2. Disconnect vacuum hose from carburetor and connect to hose from auxiliary vacuum source with small length of tube, Fig. 8. Apply at least 15 inches of vacuum.
3. Insert the specified size drill or gauge between choke valve and wall of air horn. Apply sufficient closing pressure on lever to which choke rod attaches to provide a minimum choke valve opening without distortion of diaphragm link. Note that the cylindrical stem of diaphragm will extend as internal spring is compressed. This spring must be fully compressed for proper measurement of vacuum kick adjustment.
4. An adjustment will be necessary if a slight drag is not obtained as drill or gauge is being removed. Shorten or lengthen diaphragm link to obtain correct choke opening. Length changes should be made carefully by bending (opening or closing) the bend provided in the diaphragm link. Do not apply twisting or bending force to diaphragm.
5. Reinstall vacuum hose on correct carburetor fitting. Return fast idle linkage to its original condition if it has been disturbed as in Step 1.
6. Check as follows: With no vacuum applied to diaphragm, choke valve should move freely between open and closed positions. If movement is not free, examine linkage for misalignment or interferences caused by bending operation. Repeat adjustment if necessary.