Regulating Valve

Intake side of regulating valve is connected to air distribution line, outlet side to intake manifold. Also connected to intake manifold is vacuum control line. At idle, steady speed and during acceleration the vacuum is not sufficient for opening the valve, therefore the total air volume travels to the exhaust ports. During deceleration, increased vacuum enables the diaphragm to lift momentarily thus opening the valve against the air flow. This permits compressed air to enter the intake manifold. Amount of air that enters intake manifold is in proportion to the vacuum obtained at closing of the throttle valve.