Vacuum Spark Delay Valve: Testing and Inspection

Fig. 8 Spark delay valve:

Checking spark delay valve Fig. 8.

Fig. 9 Testing spark delay valve:

1. Remove the plug from the intake manifold.
2. Disconnect the vacuum sensing tube (between spark delay valve & distributor) at the distributor and connect the tube to the intake manifold.
3. On California vehicles, disconnect the vacuum sensing tube (between the water thermo valve and spark delay valve) at the spark delay valve and connect a vacuum gauge to the delay valve, Fig. 9.
4. On high altitude vehicles, disconnect the vacuum sensing tube (between the spark delay valve and carburetor) at the carburetor and connect a vacuum gauge to the tube.
5. Disconnect the vacuum sensing tube from the intake manifold and check the required time until the vacuum reading decreases by 300 mm-Hg (11.8 in-Hg) from the vacuum at idling. The specified speed is 4-6 seconds.

Fig. 16 Testing water thermo valve:

Checking the water thermo valve.
1. Remove the water thermo valve.
2. Immerse the valve in a container with water.
3. Heat up the water gradually and observe the temperature.
4. Blow through the valve and if air flows out at 54°C (129°F) or above, the valve is satisfactory Fig. 16.