See Figure 1
The 1980 49 state models have an air induction system to supply fresh air to the exhaust manifold. The system is not used on models sold in California or Canada.
The components include an air pipe connecting the air cleaner to the exhaust manifold. An air induction valve is installed in the pipe. The valve is simply a four petal reed valve, which allows air to pass into the exhaust manifold during periods of negative exhaust pressure and closes during periods of positive exhaust pressure. In this way, fresh air is siphoned into the exhaust manifold without the need for an air pump. The fresh air promotes burning of hot HC and CO gases which otherwise would escape the combustion process.
The only periodic maintenance required is the replacement of the air induction filter at 24,000 mile (39,000 km) or 30 month intervals. This procedure is covered in General Information & Maintenance .