Ignition Timing Control System

1. Allow engine to reach normal operating temperature, then connect a tachometer and disconnect the hose from vacuum advance diaphragm on distributor and connect a vacuum gauge to hose.
2. Start engine and check for vacuum at idle.
3. If there is no vacuum, check hose connections between distributor and carburetor insulator block for leaks or blockage.
4. If there is vacuum, attach vacuum pump to vacuum advance diaphragm, start engine, and pull 20 in. Hg. vacuum.
5. If timing does not advance or will not stay advanced, replace advance diaphragm and retest.
6. Disconnect tachometer and reconnect advance hose to distributor.