Description

Fig. 25 Vacuum controlled spark timing control system. (Typical):

Fig. 26 Electrically controlled spark timing control system. (Typical):

Refer to Figs. 25 and 26 for typical spark timing control systems. Complete system schematics are located in ``Vacuum Hose Routings.''




This system incorporates a thermal vacuum valve which controls vacuum advance under varying driving conditions to reduce HC and NOx emissions. At temperatures between 59-140°F, the spark timing control system is not actuated. The system is actuated at temperatures below 59°F or above 140°F under normal driving conditions and only slightly actuated under heavy load and high speed driving.