Carburetor - ROCHESTER E2ME 2-Bbl: Description

The Rochester E2ME Dualjet is a 2 barrel, downdraft carburetor. It is used with the Computer Command Control (CCC) system of fuel control. The throttle position sensor sends a variable voltage signal input to the Electronic Control Module (ECM) in response to changes in throttle position. Its signal is used by the ECM to regulate the mixture control solenoid, Electronic Spark Control (EST), Idle Speed Control (ISC) and Torque Converter Clutch (TCC).

An electrically operated mixture control solenoid, mounted in the float bowl, is used to control air/fuel ratio. The plunger in the solenoid is controlled by electric signals received from the ECM. The solenoid is turned on and off by the ECM 10 times per second. When the solenoid is energized, the solenoid plunger pulls stepped metering rods down in the jets, causing a leaner mixture. When the solenoid is de-energized, the plunger allows the metering rod to move up in the jets, causing a richer mixture.

The solenoid adjusting (lean mixture) screw, located in the float bowl, is adjusted to obtain the correct gauge dimension between the solenoid plunger (against the solenoid stop) and the main metering jet. The rich limit stop bracket, held in place by the solenoid adjusting screw, is automatically positioned to control the solenoid plunger travel to a fixed dimension.

The air bleed valve assembly (with an identifying letter), located in the air horn, is adjusted to a gauge dimension between the solenoid plunger (against the solenoid stop) and the top of the valve. Idle mixture needles, located in the throttle body, are present to a number of turns from the lightly seated position. Final adjustment is made with the engine running, to obtain correct dwell for idle mixture control.

An idle air bleed valve, located in the air horn, is adjusted with a gauge. The mixture needles are adjusted on the vehicle for final mixture control.

NOTE: No attempt should be made to set curb idle speed with the Idle Speed Control plunger, as it is controlled by the ECM.

All carburetors are equipped with tamper-resistant features: factory-cast rich mixture stop bracket, factory-adjusted lean mixture screws, riveted choke coil housings, idle air bleed valves, TPS and idle mixture needles.

CAUTION: NO attempt should be made to adjust screws except when required by a Computer Command Control System performance check, a major overhaul, or replacement of the air horn, float bowl or throttle body.

All carburetors are equipped with a front vacuum break with a leaf-type bucking spring. Some models may use both a front and rear vacuum break to control choke valve openings during initial engine starting and cold driveaway.

All carburetors are equipped with a throttle position sensor (TPS). This sensor is a variable resistor that is used to reflect changes in throttle valve angle. One terminal to the TPS is ground. The 3rd wire is connected to the ECM to measure voltage changes from the TPS.

An idle speed control assembly is used on this carburetor to control engine idle speed by means of signals from the ECM. The ISC motor responds to commands from the ECM to open and close the throttle valves. Engine idle speed is programmed into the ECM, which controls idle speed with the carburetor throttle lever contacts (and closes) the ISC plunger switch.