E2SE Carburetor

Fig 72 - Idle Mixture Plug Removal:

Fig 73 - E2SE Carburetor Adjusting Screw Locations:

Fig 74 - Tach. & Dwell Meter Connections:

Idle mixture adjustment should only be performed if the mixture adjusting screw has been replaced or removed during carburetor overhaul. Mixture adjustments should not be made as a normal service adjustment.


Idle mixture adjustment procedures must be followed precisely because the C4 system, of which the carburetor is part, is very complex. Dwell indication from the Mixture Control (MC) solenoid is used for reference. During engine idle, it is necessary for dwell to increase and decrease over a narrow range (5°). However, dwell may vary as much as 10°-15° due to temporary abrupt mixture changes. The dwell specified for adjustments is the average for the most consistent variation.

Engine must be allowed to stabilize at idle or 3000 RPM, as applicable, before the dwell is acceptable as reference for adjustment.

1. Remove carburetor from engine and drain fuel into a suitable container.
2. Mount carburetor, manifold side up, in a suitable holding fixture.
3. Using a punch between two locator points on the throttle body manifold side, Fig. 72, breakout throttle body to gain access to the steel plug which seals the mixture adjusting screw.
4. Steel plug should shatter when driven out. It is not necessary to remove plug completely. Remove loose pieces to allow use of mixture adjusting tool.
5. Turn mixture adjusting screw in (clockwise) until lightly seated then back screw out 3 full turns on automatic transmission models and 2 1/2 turns on manual transmission models.
6. If plug covering idle air bleed adjusting screw has been removed, turn bleed screw, Fig. 73' clockwise until lightly seated, then back screw out 1 1/4 turns. If plug is in place, adjustment is not required.
7. On 1980-81 models, remove vent stack screen assembly to gain access to lean mixture adjusting screw. Turn lean mixture screw, Fig. 73, in until lightly seated, then back screw out 3 full turns.
8. Install carburetor on engine with air cleaner off and related vacuum hoses.
9. Disconnect EGR and canister purge hoses at carburetor and plug ports.
10. Connect tachometer to distributor "tach" wire connector and connect dwell meter to MC solenoid test wire connector, Fig. 74.
11. With transmission in park (manual in neutral), start engine and operate at fast idle for 3 minutes to allow C4 system to enter "Closed Loop" mode of operation.
12. On 1980-81 models, operate engine at 3000 RPM and adjust lean mixture screw to obtain average dwell reading of 35°. Adjust screw in small increments to allow dwell to stabilize. If reading is too high, turn screw clockwise; if reading is too low, turn screw counter-clockwise.

NOTE: If unable to adjust to specifications, check main metering circuit for leaks, restrictions, etc.

13. Return engine to idle and adjust idle speed to 700 RPM.
14. Turn idle mixture adjusting screw to obtain dwell reading of 25°. Adjustment is very sensitive; allow dwell to stabilize between adjustments. If reading is too high, turn screw clockwise; if reading is too low, turn screw counter-clockwise.

NOTE: Make final check with tool removed. If unable to adjust to specifications, check idle circuit for leaks, restrictions, etc.

15. Disconnect wiring harness connector to MC solenoid. If engine speed does not change by more than 50 RPM, inspect air bleed circuit for leaks or restrictions. Reconnect wiring harness connector to MC solenoid.
16. On 1980-81 models, repeat step 12. If correct dwell is not indicated on meter, readjust lean mixture screw, then adjust idle mixture screw.
17. Reconnect vacuum hoses. On 1980-81 models, make sure vent stack screen is properly installed. set idle speed to specifications and install air cleaner.