Thermostatic Air Cleaner: Description and Operation

Fig. 24 Typical heated air intake system:

This system is used to maintain the temperature of the air entering the carburetor at a constant and predetermined temperature. In cold weather, this system directs a hot air supply to the carburetor to improve driveability and prevent carburetor icing.

When the engine is cold, the thermo valve is closed and the intake manifold acts on the diaphragm and draws it up. Raising the diaphragm causes the link to pull up the air control valve which closes the cold air passage and opens the hot air passage which is around the exhaust manifold, Fig. 24, acts on the diaphragm and the diaphragm is pushed down by spring tension. The air control valve is lowered to open the cold air passage and close the hot air passage.