Every 8,000 miles (13,000 km) on 1970-74 models check the function of the air intake flap as follows:
- With the engine cold, remove the fresh air intake line at the air cleaner. The outside temperature should be cool, preferably 70°F (21°C) or below.
- Start the engine and immediately observe the flap. It should close tightly. Shut the engine off and verify that the valve opens all the way.