The AIR system (first introduced on California cars in 1966) was used on most early model vehicles covered in this guide through 1980. A form of the system may be found on all 231 V6 engines as late as 1984. In the early 1980's most other engines for the Chevrolet mid-sized vehicles changed to another, very similar, system known as Air Management which is covered later in this section.
The AIR system injects compressed air into the exhaust system near the exhaust valves. The fresh air allows exhaust gases, which normally remain unburned as they are expelled from the system, to continue burning and thereby lower emissions. 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.
The AIR system on the 231 V6 engine is slightly different, but its purpose remains the same.
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. Refer to the engine tune-up procedures in of this guide for more information on engine settings. In addition to engine control adjustments, all hoses and fittings should be inspected for condition and connection tightness. Check the drive belt for wear and tension every 12 months or 12,000 miles.
REMOVAL & INSTALLATION
- Disconnect the air hose(s) at the pump.
- If necessary, hold the pump pulley form turning and loosen the pulley bolts.
- Loosen the pump mounting bolt and adjustment bracket bolt. Remove the drive belt.
- Remove the mounting bolts, and then remove the pump.
- Position the pump in the vehicle and loosely install the mounting bolts
- If loosened or removed, install and tighten the pulley bolts.
- Position the drive belt over the pulley, then adjust the belt tension and tighten the pump bolts.
- Connect the air hose(s) to the pump.
- Detach the vacuum sensing line from the valve.
- Disconnect the remaining hose(s) from the valve.
- Unfasten the diverter valve from the elbow or the pump body and remove the valve from the vehicle.
- Install the diverter valve to the elbow or the pump body using a new gasket.
- Tighten the valve securing bolts to 85 inch lbs. (10 Nm).
- Connect the vacuum sensing line and hoses(s) to the valve.