Mixture Adjustment A

Fig. 8a Idle Mixture screw base adjustment position. M2MC-ME & M4MC-ME carburetors:

Fig. 7 Idle air bleed valve adjustment. E2MC-ME & E4MC-ME carburetors:

1. Install gauging tool J-33815-2 or equivalent in ``D'' shaped hole on throttle side of air horn, with end of tool positioned above open cavity next to idle air bleed valve, Fig. 7.
2. Hold gauge down lightly to bottom MC solenoid plunger, then adjust idle air bleed valve so tool will pivot over and just contact top of valve. Remove gauging tool.
3. Start engine and run until it reaches normal operating temperature and dwell reading begins to fluctuate.
4. Place automatic transmission in Drive (manual transmission in Neutral) and adjust idle air bleed valve to obtain a fluctuating dwell reading between 25° and 35° (as close to 30° as possible), at specified curb idle speed. Bleed valve is very sensitive to adjustment. Adjust valve in small increments, allowing time between adjustments for engine to stabilize.
5. If unable to adjust dwell reading to specifications, or if reading does not fluctuate, remove plugs covering idle mixture screws as outlined in ``Concealment Plug Removal'' in the Carburetor Section.
6. Turn each mixture screw in (clockwise) until lightly seated, then back screws out specified number of turns, Fig. 8.
7. Reinstall carburetor using a new gasket, with air cleaner removed, and vacuum hoses disconnected and plugged as outlined on underhood vehicle emissions label.
8. Repeat steps 3 and 4. If unable to obtain specified dwell reading, proceed as follows:
a. If reading is below 25°, turn mixture screws counterclockwise 1 turn, then repeat steps 3 and 4.
b. If reading is above 35°, turn mixture screws clockwise 1 turn, then repeat steps 3 and 4.
c. If unable to adjust dwell to specifications, or if reading does not fluctuate, refer to diagnosis in the Emission Control Section.
9. Stop engine. Seal mixture screw cavities with RTV sealer and install bleed valve cover.
10. Reinstall air cleaner and reconnect vacuum hoses, then check curb idle speed.