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