EGR System: Description
The Exhaust Gas Recirculation (EGR) system lowers combustion temperatures in combustion chamber, thereby reducing emission of oxides of nitrogen. Exhaust gas is drawn from cylinder head exhaust port into intake manifold riser portion through passages in cylinder head, intake manifold, and EGR valve.
The EGR valve vacuum diaphragm is connected to carburetor flange signal port through a Thermal Vacuum Valve (TVV). This controls EGR cold override. Opening carburetor throttle valve applies a vacuum to diaphragm, opening EGR valve to meter exhaust gas into intake manifold.