(START UP - DECELERATION SYSTEM 5200C-2V)

The automatic choke assembly is mounted on the carburetor body. It has a bimetal thermostatic coil which winds up when cold, and unwinds when hot. A vacuum diaphragm and spring controls the initial operation of the choke. Engine coolant, flowing through a choke water cover, heats the bimetal coil and controls the final choke opening.

To start the engine, the accelerator pedal is depressed, closing the choke valves. This permits fuel to flow through the main metering system as well as the idle system. When the engine starts, air flows past the off-set choke valves and manifold vacuum, acting on the choke vacuum diaphragm, opens the choke valves to the predetermined position. As the engine coolant warms up, it circulates through the choke housing, heating the bimetallic choke coil. The coil unwinds, permitting full opening of the choke valves. If the cold engine is suddenly accelerated, the resulting drop in manifold vacuum on the vacuum diaphragm allows the choke valves to momentarily close.

The fast idle camp, actuated by the choke rod, controls idle speed during engine warm-up. When the choke valves are fully opened, the fast idle cam rotates free of the fast idle screw. An unloader tang on the throttle lever partially opens the choke valves when the accelerator is fully depressed. This permits unloading or breathing of a flooded engine. During deceleration there is a high vacuum condition, causing fuel from the bowl to pass through a restriction where it is mixed with air from another calibrated restriction. This mixture passes through a horizontal passage where it is mixed with a larger quantity of air, and then flows through a vacuum-operated deceleration alve into the intake manifold.