Ported EGR System
Ported type EGR valve is operated from carburetor vacuum port. It is fully closed with vacuum less than 2", it starts to open above 2" and is fully open with more than 8.5" of vacuum applied. At idle and wide open throttle, ported vacuum is low, the valve is closed and recirculation does not occur. At part throttle, ported vacuum is high, the valve is open and exhaust gas recirculation is at maximum.