Venturi Vacuum Control System

A vacuum tap at throat of carburetor venturi is used to provide control vacuum. Because of the low amount of vacuum, it is necessary to use a vacuum amplifier to increase vacuum to a level required to operate E.G.R. valve. Elimination of recycle at wide open throttle is accomplished by a dump diaphragm which compares venturi and manifold vacuum to determine when wide open throttle is reached. At wide open throttle, the internal reservoir is "dumped", limiting output to E.G.R. valve opening point. Opening point is set above manifold vacuum available at wide open throttle, permitting E.G.R. valve to be closed at wide open throttle.