Air Cleaner - Thermostatic: Description
All models use a system for preheating air entering carburetor. Vacuum motor, part of the air cleaner, maintains air temperature at a point where carburetor/throttle body can be calibrated much leaner to reduce hydrocarbon (HC) emissions while also improving warm-up operations and reducing carburetor icing.
System consists of air cleaner assembly, integral air control door, vacuum control temperature sensor, vacuum motor, heat shroud (on exhaust manifold) with connecting pipe and vacuum hoses. Some models use additional controls, such as vacuum traps and cold weather modulators.