With Timing Light

Ignition distributor, checking centrifugal advance with timing light

- Connect tester according to manufacturer's instructions.
- Pull both hoses off distributor vacuum unit.
- Disconnect plugs from idle stabilizer and connect together.
- Start engine and adjust idle speed to 900 RPM.
- Shine timing light on timing mark and note indicated angle (basic angle)

Note: Start of centrifugal advance is shown by movement of notch while increasing RPM.

- Increase engine speed slowly to 1600 RPM.
- Bring back notch to original setting by turning knob on tester. Read off advance value.

Note: To determine centrifugal advance, subtract basic advance angle from last advance angle measured.
Example: last advance angle measured (-) minus basic advance angle

- Repeat check at other test speeds.
- Reconnect vacuum hose when test completed.
- Adjust idle speed.