Designed to increase the idle rpm for smoother running when the engine is cold, the fast idle cam has a series of steps on one edge. As the choke lever is moved through its range of travel from the closed position to the open position, the fast idle cam rotates, presenting successive steps to a throttle stop screw. Each step permits a slower idle rpm as engine temperature rises and choking is reduced.
							2.   SECONDARY SYSTEM
							A. FUEL INLET - Fuel is supplied to the secondary fuel bowl through a connecting tube at the primary fuel inlet. The secondary fuel bowl is equipped with a fuel inlet valve assembly which regulates the flow of fuel into the bowl the same as the primary fuel bowl.
		Automatic Choke					The secondary fuel inlet system must maintain a specified level of fuel as the secondary fuel system is calibrated to deliver the proper
	(2) AUTOMATIC CHOKE - Some car buretor models have an automatic choke which is controlled by hot air. The automatic choke is mounted on the main body or in the exhaust cross over passage of the intake manifold and is linked to the choke shaft, which controls the air flow into the carburetor.
	The automatic choke is equipped with a bi-metallic thermostat spring and a vacuum piston. The vacuum piston on the 4160 with mechanical secondarys is located in the main body of the car buretor. They are connected to the choke shaft by means of levers and linkage. When the engine is cold, the bi-metal spring closes the choke plate for starting. When the engine fires, manifold vacuum is applied to the choke piston which, with the help of air flow on the offset choke plate, opens the choke plate against the tension of the cold bi-metal spring. These pieces have been engineered to allow enough air to enter the engine and keep it running.
	While the engine warms-up, hot air is circulated through the choke housing or through the exhaust cross over passage of the intake manifold to warm the bi-metal spring. As the bi-metal spring gets warm, it will release its tension on the choke shaft and allow the choke plate to gradually open. The path for the hot air is from heat in the exhaust manifold, into the choke housing, through the small slots in the choke piston, through passages in the carburetor and then into the intake manifoldfor all models except the 4160 with mechanical secondarys. This model has the bi-metal spring mounted in the exhaust crossover of the intake manifold. The di vorced choke assembly is serviced as a unit.
	There is a choke lever on the carbure tor which actuates a fast idle cam during choking.
								Secondary Idle and Transfer System