Early Fuel Evaporation ( EFE ): Description and Operation

Fig. 35 Typical heated air intake system:

Heated intake air, Fig. 35 is used during engine warm-up to improve driveablity. To achieve overall emission performance the carburetor is calibrated overly lean and heated intake air is used during engine warm-up to eliminate carburetor icing and improve cold engine performance and driveablity.

The air cleaner housing snorkel is equipped with an air control valve that mixes warm air from the exhaust manifold heat cowl with cold air from the snorkel. The air control valve is operated by a vacuum motor that actuates the air control valve. The vacuum motor is controlled by a bi-metalic spring bleed valve which regulates the vacuum control signal.