Air Cleaner Housing: Description and Operation

Fig. 40 Air Control Door:

The air cleaner supplies filtered, temperature controlled air to the carburetor. It incorporates a pleated paper filter as well as an air control diaphragm that directs intake airflow into the engine. When the air cleaner temperature is below 100°F (37°C) vacuum is applied to the air control diaphragm which forces heated air to be drawn off the exhaust manifold. When the temperature is above 100°F (37°C) vacuum is allowed to bleed off through a bimetallic valve in the air cleaner allowing normal airflow into the engine. The air cleaner mounted air bleed also incorporates a check valve which prevents vacuum loss from the air control diaphragm during high load conditions. For further information refer to EMISSION CONTROLS.