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Spark Advance of Computer

  1. Start engine and allow it to warm to normal operating temperature. Put transmission in neutral and set parking brake.
    NOTE: The Spark Control Computer has various spark advance schedules incorporated into its microprocessor for operation at differing engine temperatures. Therefore, be sure engine is at normal operating temperature before testing.
  2. Place a thin insulator (piece of paper) between curb idle adjusting screw and carburetor switch, or make sure screw is not touching switch. See Figure. Remove and plug vacuum line at vacuum transducer.
  3. Connect an auxiliary vacuum supply to vacuum transducer and set for 16 in. Hg vacuum. Increase engine speed to 2000 RPM, wait one minute for specified accumulator clock up time, and then check specifications. Advance specifications are in addition to basic advance.
    CAUTION: Use a metal exhaust tube for this test, as high temperatures could cause rubber hose to catch fire.
  4. If computer fails to obtain specified settings, replace computer.
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