Back Pressure EGR Valve
The negative transducer back pressure EGR valve assembly has the same function as positive back pressure EGR valve except transducer is designed to allow valve to open with negative exhaust back pressure.
Flow of valve is controlled by manifold vacuum, negative exhaust back pressure and carburetor ported vacuum signal. Control valve spring in transducer is placed on bottom side of diaphragm.
When carburetor ported vacuum signal is applied to main vacuum chamber partially opening valve, vacuum signal from manifold side (reduced by exhaust back pressure) is transmitted up the hollow stem of valve. This enables signal to act on diaphragm, opening bleed and causing transducer to modulate providing a specific valve flow. Thus flow of valve is a constant percentage of engine air flow.