ROCHESTER Models 2SE & E2SE 2-Barrel: Description

The Rochester models 2SE & E2SE are 2-stage, 2-barrel downdraft carburetors. The primary stage consists of a triple venturi with a 35 mm bore. The secondary stage has a 46 mm bore and is equipped with an air valve with a single tapered metering rod. Both are equipped with integral electronically activated chokes, a choke vacuum break diaphragm and an idle speed solenoid.

The E2SE model is used in conjunction with the Computer Controlled Catalytic Converter System (C-4). The carburetor is equipped with an electrically actuated mixture control solenoid mounted in the air horn. Fuel metering is controlled by the mixture control solenoid plunger opening and closing and fuel passage to the main metering jet.

This opening and closing action causes a variable restriction of fuel to the main metering circuit, changing air/fuel ratio. Also, air metered to the idle system is controlled by the movement of the mixture control solenoid plunger.

The solenoid is activated by an electronic signal from the Electronic Control Module (ECM). The ECM responds to a signal from the oxygen sensor in the exhaust, then energizes the solenoid to move the plunger down to a lean position or de-energizes solenoid to move plunger up to a rich position. Air metered (by solenoid plunger) to idle system is controlled by an idle air bleed valve located in the air horn. This valve follows movement of the mixture control solenoid.

On E2SE models, a Throttle Position Sensor (TPS) is used to signal the ECM of throttle position changes as they occur. When throttle position is changed, a tang on the pump lever moves TPS plunger. This signals the ECM to hold the last known air/fuel ratio to aid in throttle response.