Idle Speed/Mixture
IDLE SPEED/MIXTURE INSPECTIONPropane Enrichment Method
NOTE:
- This procedure requires a propane enrichment kit
- Check that propane bottle has adequate gas before beginning test.
WARNING: Do not smoke during this procedure. Keep any open flame away from your work area.
1. Start the engine and warm up to normal operating temperature (the cooling fan goes on at least twice).
2. Remove the vacuum hose from intake air control diaphragm and clamp the hose end
3. Connect tachometer.
4. Check idle speed with the headlights, heater blower, rear window defroster, cooling fan and air conditioner off.
Idle Speed should be:
NOTE: The lower rpm number is if idle is measured at high altitude; the high rpm number is if idle is measured at low altitude.
Adjust the idle speed, if necessary, by turning the throttle stop screw.
5. Disconnect air cleaner intake tube from air duct on radiator bulkhead.
6. Insert the hose of the propane enrichment kit into the intake tube about 4 inches.
7. With engine idling, depress push button on top of propane device, then slowly open the propane control valve to obtain maximum engine speed. Engine speed should increase as percentage of propane injected goes up.
NOTE: Open the propane control valve slowly; a sudden burst of propane may stall the engine.
- If engine speed does not increase per specification, mixture is improperly adjusted. Go to step 8.
- If engine speed increases per specification, go to step 21.
8. Remove air cleaner.
9. Disconnect all vacuum hoses from the carburetor.
10. Pull the brake booster hose and the throttle cable out of the their brackets.
11. Remove the carburetor nuts and washers.
12. Lift the carburetor clear of its studs; then tilt it backwards so you can remove the throttle controller bracket screw.
13. Remove the throttle controller bracket.
14. Remove the mixture adjusting screw hole cap from the throttle opener bracket, then reinstall the bracket.
15. Reinstall the carburetor, but first check the insulator block for damage.
16. Reconnect the vacuum hose to the fast idle unloader.
17. Install the air cleaner.
18. Start engine and warm up to normal operating temperature; the cooling fan will come on.
19. Remove the vacuum hose from intake air control diaphragm and clamp the hose end.
20. Reinstall the propane enrichment kit and recheck maximum propane enriched rpm.
- If the propane entriched speed is too low, mixture is too rich: turn the mixture screw 1/4-turn clockwise and recheck.
- If the propane enriched speed is too high, mixture is too lean: turn the mixture screw 1/4-turn counterclockwise and recheck.
21. Close the propane control vatve and recheck idle speed.
NOTE: Run the engine at 2,500 rpm for 10 seconds to stabilize condition.
- If idle speed is as specified (step 4), go to step 23.
- If idle speed is not as specified (step 4), go to step 22.
22. Recheck idle speed and, if necessary, adjust by turning throttle stop screw, then repeat steps 20 and 21.
23. Remove propane enrichment kit and reconnect air cleaner intake tube on the radiator bulk head.