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GM Cadillac 1967-1989 Repair Guide

Controlled Combustion System


The CCS system 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 CCS equipped models to ensure that air entering the carburetor is kept at 100°F (38°C). This allows leaner carburetor settings and improves engine warm-up. A higher temperature thermostat is employed on CCS cars to further improve emission control.


Since the only extra component added with a CCS system 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 ensure that these settings are correct, both for trouble-free operation and a low emission level.