Idle Mixture and Speed Adjustments

1. Apply parking brake and block front wheels. Disconnect automatic brake release, if equipped and plug vacuum connection.
2. Connect a suitable tachometer to the engine.
3. Ensure hot idle compensator, if equipped, is in the closed position.
4. Disconnect and plug fuel evaporative purge return hose from engine. Disconnect and plug fuel evaporative purge hose from air cleaner. Plug air cleaner nipple.
5. Disconnect flexible fresh air tube from air cleaner duct or adaptor.
6. Using propane enrichment tool, Rotunda Tool T75L-9600-A or equivalent, insert tool hose approximately 3/4 of the way into the duct or fresh air tube. If necessary, secure hose with suitable tape.
7. On vehicles equipped with Thermactor System, note the following:
a. For dump valves with 2 vacuum fittings, disconnect and plug the hoses.
b. For dump valves with one fitting, disconnect and plug hose from dump valve. Connect a suitable hose from dump valve fitting to an intake manifold fitting.
c. On 4-140 engines, disconnect and plug hoses from dump valve portion of the combination dump valve and air diverter valve.
d. On vehicles equipped with feedback carburetors, disconnect wires from electric PVS.