Chevrolet Full-size Cars 1968-1978 Repair Guide

Air Injection Reactor System (AIR)

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OPERATION



The AIR system injects compressed air into the exhaust system, near enough to the exhaust valves to continue the burning of the normally unburned segment of the exhaust gases. To do this it employs an air injection pump and a system of hoses, valves, tubes, etc., necessary to carry the compressed air from the pump to the exhaust manifolds. Carburetors and distributors for AIR engines have specific modifications to adapt them to the air injection system; those components should not be interchanged with those intended for use on engines that do not have the system.

A diverter valve is used to prevent backfiring. The valve senses sudden increases in manifold vacuum and ceases the injection of air during fuel-rich periods. During coasting, this valve diverts the entire air flow through the pump muffler and during high engine speeds, expels it through a relief valve. Check valves in the system prevent exhaust gases from entering the pump.

SERVICE



The AIR system's effectiveness depends on correct engine idle speed, ignition timing, and dwell. These settings should be strictly adhered to and checked frequently. All hoses and fittings should be inspected for condition and tightness of connections. Check the drive belt for wear and tension every 12 months or 12,000 miles.

REMOVAL & INSTALLATION





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Fig. Fig. 1 Exploded view of the Air Injection Reaction (AIR) system and related components for the inline six cylinder engine



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Fig. Fig. 2 View of the Air Injection Reaction (AIR) system used on some early model V8 engines



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Fig. Fig. 3 Exploded view of the AIR system and related components used on later model V8 engines



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Fig. Fig. 4 Using a pair of needlenose pliers to remove the fan from the air pump

Air Pump

WARNING
Do not pry on the pump housing or clamp the pump in a vise; the housing is soft and may become distorted.

  1. Disconnect the air hoses at the pump.
  2.  
  3. Hold the pump pulley form turning and loosen the pulley bolts.
  4.  
  5. Loosen the pump mounting bolt and adjustment bracket bolt. Remove the drive belt.
  6.  
  7. Remove the mounting bolts, and then remove the pump.
  8.  
  9. Install the pump using a reverse of the removal procedure.
  10.  

Diverter (Anti-afterburn) Valve
  1. Detach the vacuum sensing line from the valve.
  2.  
  3. Remove the other hose(s) from the valve.
  4.  
  5. Unfasten the diverter valve from the elbow or the pump body.
  6.  
  7. Installation is performed in the reverse order of removal. Always use a new gasket. Tighten the valve securing bolts to 85 inch lbs.
  8.  

Pump Filter
  1. Remove the drive belt and pump pulley.
  2.  
  3. Using needlenosed pliers, pull the fan from the pump.
  4.  

Use care to prevent any dirt or fragments from entering the air intake hole. DO NOT insert a screwdriver between the pump and the filter, and do not attempt to remove the metal hub. It is seldom possible to remove the filter without destroying it.

  1. To install a new filter, draw it on with the pulley and pulley bolts. DO NOT hammer or press the filter on the pump.
  2.  
  3. Draw the filter down evenly by torquing the bolts alternately. Make sure the outer edge of the filter slips into the housing. A slight amount of interference with the housing bore is normal.
  4.  

The new filter may squeal initially until the sealing lip on the pump outer diameter has worn in.

 
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