Air Injection: Description and Operation

CAUTION: Due to design differences, carburetors and distributors for engines equipped with air pump systems should not be interchanged with carburetors or distributors designed for engines without air pump systems.

Fig 1 Air Pump System W/ Mixture Control Valve:

Fig. 2 Air Pump System W/ Diverter Valve:

The Air Injection Reactor (AIR) System reduces emissions of hydrocarbons and carbon monoxide by pumping fresh air into the exhaust system--near the exhaust valves--where the oxygen in the fresh air is used to burn any unburned fuel.

Fig. 3 - Air Pump W/ Separate Filter:

Fig. 4 - Air Pump W/ Centrifugal Filter & Pressure Relief Valve:

Fig. 5 - Air Pump W/ Centrifugal Filter Less Pressure Relief Valve:

Air pump systems used--Figs 1 and 2--consist of a belt driven air injection pump--Figs 3, 4 and 5--air injection tubes (one for each cylinder), an air bypass valve, a mixture control valve 1966-67 models or diverter valve 1968-82 models, a differential vacuum delay valve, a separator valve, a vacuum differential valve (California only) and check valves (one for In-Line engines, two for V8's).

NOTE: Not all systems contain all components listed above.

Fig. 6 - Mixture Control Or Backfire Bypass Valve:

MIXTURE CONTROL OR BACKFIRE BYPASS VALVE
The mixture control or backfire bypass valve--Fig 6--prevents exhaust backfire on deceleration by supplying fresh air to the intake manifold to lean out the fuel/air mixture. The valve is triggered by the sharp increase in manifold vacuum caused by the sudden closure of the throttle valve.

Fig. 4 - Air Pump W/ Centrifugal Filter & Pressure Relief Valve:

Fig. 7 - Diverter Or Air Bypass Valve W/O Pressure Relief Valve:

Fig. 8 - Diverter Or Air Bypass Valve W/ Pressure Relief Valve:

DIVERTER OR AIR BYPASS VALVE
The diverter or air bypass valve--Figs 7 and 8--when triggered by a sharp increase in manifold vacuum, shuts off injected air to the exhaust preventing backfiring during this richer period.

On engine overrun the total air supply is dumped through the diverter valve muffler.

At high engine speeds excess air is dumped through the pressure relief valve located either in the pump assembly--Fig 4--or the diverter valve--Fig 8.


CHECK VALVES
Check valves protect the the hoses and pump by preventing hot gases from backing up into the system while allowing fresh air to circulate from the pump to the exhaust ports.

NOTE: A properly operating AIR system effectively reduces emissions however if any component related to the system malfunctions emissions may be increased.

NOTE: Carburetors, distributors and control valves are designed for specific engine applications and should not be interchanged with other units.