Air Cleaner
When temperature of intake air is low with engine running, air control valve closes underhood air intake and allows only heated air from shroud around exhaust manifold to enter air cleaner. When intake air reaches about 100°F (all except 240 Z & 1200) or 110°F (240 Z & 1200) sensor actuates to start to open air control valve. At about 118°F (all except 240 Z & 1200) or 120°F (240 Z & 1200) air control valve will completely open to prevent entrance of hot air and allow only engine compartment air to enter air cleaner. When engine is operated under a heavy load (high manifold vacuum) air control valve opens fully to underhood air intake to obtain full power regardless of air temperature. This control of air temperature allows leaner carburetor settings with accompanying reduced emissions and also eliminates carburetor icing.