Before making any adjustments, check the injection timing, and adjust if necessary. Also note that these adjustments should be performed together. The vacuum valve adjustment (THM350's only) on 1979 and later models requires the use of several special tools. If you do not have these tools at your disposal, refer the adjustment to a qualified, professional technician.
See Figure 1
- If equipped with cruise control, remove the clip from the control rod, then remove the rod from the bellcrank.
- Remove the throttle valve cable (THM200) or detent cable (THM350) from the bellcrank.
- Loosen the locknut on the throttle rod, then shorten the rod several turns.
- Rotate the bellcrank to the full throttle stop, then lengthen the throttle rod until the injection pump lever contacts the injection pump full throttle stop. Release the bellcrank.
- Tighten the throttle rod locknut.
- Connect the throttle valve or detent cable and cruise control rod to the bellcrank. Adjust if necessary.
THROTTLE VALVE (TV) OR DETENT CABLE
See Figure 21979-82 Models
- Make sure the ignition switch is off. Depress and hold the metal readjustment tab all the way down. This is located on the engine end of the Throttle Valve cable. Move the slider until it is located directly against the fitting, and then release the adjustment tab.
- Rotate the throttle lever to give wide open throttle position. Watch the slider as you do this; it must move toward the lever as you rotate the throttle. If the slider works properly, this will complete the adjustment.
After the adjustment, make sure the cable works freely after the engine has warmed to operating temperature.1983-84 Models
- Disconnect the transmission detent cable from the throttle assembly. If the vehicle has cruise control, disconnect it from the cruise control servo rod as well.
- Depress and hold the metal lock tab on the upper end of the cable. Move the slider through the fitting away from the bellcrank lever assembly until the slider stops against the metal fitting. Release the metal tab.
- Install the cruise control serve rod if the vehicle has cruise control. Reconnect the cable. Then, rotate the bellcrank lever assembly until it reaches the full throttle stop and release it.
See Figure 3
- Remove the throttle rod from the bellcrank.
- Loosen the transmission vacuum valve attaching bolts just enough to disengage the valve from the injection pump shaft.
- Hold the injection pump lever against the full throttle stop.
- Rotate the valve to the full throttle position, then insert a 0.090 in. (2.28mm) pin to hold the valve in the full throttle position.
- Rotate the assembly clockwise until the injection pump lever is contacted.
- While holding the assembly in contact with the lever, tighten the two bolts holding the vacuum valve to the pump, remove the pin and release the lever, and reconnect the throttle rod to the bellcrank.
See Figures 4, 5, 6 and 7
- Remove the air cleaner assembly.
- Remove the air intake crossover from the intake manifold. Cover the intake manifold passages to prevent foreign material from entering the engine.
- Disconnect the throttle rod from the injection pump throttle lever.
- Loosen the transmission vacuum valve-to-injection pump bolts.
- Mark and disconnect the vacuum lines from the vacuum valve.
- Attach a carburetor angle gauge adapter (Kent-Moore tool J-26701-15 or its equivalent) to the injection pump throttle lever. Attach an angle gauge (J-26701 or its equivalent) to the gauge adapter.
- Turn the throttle lever to the wide open throttle position. Set the angle gauge to 0.
- Center the bubble in the gauge level.
- Set the angle gauge to the correct setting according to the year and type of engine.
- Attach a vacuum gauge to port 2 and a vacuum source (e.g. hand-held vacuum pump) to port 1 of the vacuum valve (as illustrated).
- Apply 18-22 in. Hg of vacuum to the valve. Slowly rotate the valve until the vacuum reading drops to the correct value.
- Tighten the vacuum valve retaining bolts.
- Reconnect the original vacuum lines to the vacuum valve.
- Remove the angle gauge and adapter.
- Connect the throttle rod to the throttle lever.
- Install the air intake crossover, using new gaskets.
- Install the air cleaner assembly.