Automatic advance and retard mechanism - for spark ignition engines operates pneumatically according to position of throttle valve

摘要

Automatic advance and retard of the spark is an effective way of improving combustion and thus reducing pollution and increasing the efficiency of the engine. The mechanism offers instantaneous response to throttle position. There are two bleed holes in the air intake duct (3) downstream of the throttle valve (2) and (4) upstream of the throttle valve. The pressure difference between (3) and which depends on the throttle position is communicated via a transmitter valve to a diaphragm valve (5). The transmitter is spring loaded so as to provide damping for the movement of the valve. The diaphragm valve is connected by a mechanical link to the distributor base, to allow it to rotate.