HITACHI DCG 306, DCH 306, DCJ 306 & DCP 306 2 Barrel: Description

Carburetor is a two barrel downdraft design with primary and secondary throttle systems. A choke valve and idle circuit are used in primary system only. Both primary and secondary Venturis have main fuel nozzles. When the primary throttle valve is nearly wide open, secondary throttle valve begins to open. An auxiliary throttle valve, located above secondary throttle valve, provides smooth operation as secondary begins to open. A mechanical accelerator pump and vacuum operated power valve are used for increased fuel requirements. An anti-dieseling solenoid valve is used to stop fuel flow in idle circuit (on some models) when the ignition switch is turned off. To control exhaust emissions, Subaru uses a coasting by-pass system, Mazda an anti-afterburn valve and throttle opener system, and Datsun uses a throttle opener control system (except on California models). All models use an electric choke system. Some models use an altitude compensation device to maintain optimum air/fuel ratio at higher altitudes as the air becomes less dense.