Chevrolet Nova/ChevyII 1962-1979

Controlled Combustion System (CCS)



CCS relies upon leaner air/fuel mixtures and altered ignition timing to improve combustion efficiency. A special air cleaner with a thermostatically controlled opening is used on most models equipped with CCS to make sure that air entering the carburetor is kept at 100°F. This allows leaner carburetor settings and improves engine warm-up. A higher temperature thermostat (15°F higher) is employed on CCS cars to further improve emission control.


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Fig. Fig. 1 View of the Thermac air cleaner and related components

Since the only extra component added to CCS vehicles is the thermostatically controlled air cleaner, there is no additional maintenance required; however, tune-up adjustments such as idle speed, ignition timing, and dwell become much more critical. Care must be taken to make sure that these settings are correct, both for trouble-free operation and a low emission level.