In order to extract the full measure of performance and economy from your engine it is essential that it is properly tuned at regular intervals. A regular tune-up will keep your cars engine running smoothly and will prevent the annoying breakdowns and poor performance associated with an untuned engine.
All 1968-74 cars use a conventional breaker point ignition system. In 1975, Chevrolet switched to a full electronic ignition system known as HEI.
A complete tune-up should be performed at least every 15,000 miles (12,000 miles for early cars) or twelve months, whichever comes first.
This interval should be halved if the car is operated under severe conditions such as trailer towing, prolonged idling, start-and-stop driving, or if starting or running problems are noticed. It is assumed that the routine maintenance described in has been kept up, as this will have a decided effect on the results of a tune-up. All of the applicable steps of a tune-up should be followed in order, as the result is a cumulative one.
If the specifications on the underhood tune-up sticker in the engine compartment of your car disagree with the Tune-Up Specifications chart in this information, the figures on the sticker must be used. The sticker often reflects changes made during the production run.