Air Flow Sensor

Fig. 11 Air Flow Sensor:

The air flow sensor, Fig. 11, consists of an air venturi tube inside of which moves an air flow sensor plate. The air flowing into the venturi lifts the air flow sensor plate, thereby allowing air passage. The more air passing the plate, the higher the plate is raised.
The airflow sensor plate is mounted on a lever and is compensated by a counter weight. The lever acts upon the control plunger in the fuel distributor, which has fuel pressure on the other end pushing it down.
The lever's movement of the control plunger is adjustable by means of an adjusting screw on the air flow sensor link. The CO mixture adjustment is made by turning this screw. The adjustment requires a special tool, and the screw is only accessable when the access plug has been removed.

Fig. 12 Air Flow Sensor Venturi:

Since the air/fuel mixture varies with the engine load, the venturi walls have a built in variable inclination, Fig. 12, to provide the correct air/fuel mixture at all loads.