Spark Control Systems Diagnosis & Testing

6-258 & V8-360 WITH STANDARD COOLING SYSTEM

1. Connect a suitable vacuum gauge to center port (port D) of CTO valve.
2. Manifold vacuum should be indicated on gauge when coolant temperature is below 155° F. Above this temperature, carburetor ported vacuum should be indicated. If defective, replace valve. Ported vacuum is only available when the throttle is opened to obtain an engine speed of approximately 1000 RPM.



6-258 & V8-360 WITH HEAVY DUTY COOLING SYSTEM

1. Connect a suitable vacuum gauge to port D (Dist.) of CTO valve.
2. When coolant temperature is below 220° F, carburetor ported vacuum should be indicated on gauge. When temperature exceeds 220° F, manifold vacuum should be indicated. If defective, replace valve.




DUAL RANGE CTO VALVE

6-258 & V8-360

1. Connect a suitable vacuum gauge to port D (Dist.) of CTO valve.
2. When coolant temperature is below 149° F, or above 220° F, manifold vacuum should be indicated on gauge. When temperature is between 149° F and 220° F, carburetor ported vacuum should be indicated. If defective, replace valve.




NON-LINEAR VACUUM REGULATOR (NLVR) VALVE

6-258 & V8-360

1. Connect a suitable vacuum gauge to port D (Dist.) of NLVR valve.
2. Start and run engine at idle speed. Vacuum gauge should indicate approximately 7 in. Hg.
3. As engine speed is increased, carburetor ported vacuum should be indicated. If defective, replace valve.

Fig. 25 Forward delay valve test time limits:

FORWARD DELAY VALVE

6-258 & V8-360

1. Connect an external vacuum source to port on black or red side of valve.
2. Connect one end of a 24 inch length of rubber hose to vacuum gauge and opposite end to port on colored side of valve.
3. Apply a constant vacuum of 10 in. Hg and note the time required for gauge to move from 0 to 8 in. Hg. Refer to Fig. 25 for applicable time limits.
4. If defective, replace valve. If original valve is satisfactory, reinstall it with black or red side toward vacuum source. In addition to the valves listed in Fig. 25 some engines incorporate a two-way delay valve, identified by an orange body. Minimum and maximum time limits for this valve are 0.2 to 0.4 seconds.

Fig. 26 Reverse delay valve test time limits:

REVERSE DELAY VALVE

6-258 & V8-360

1. Connect an external vacuum source to colored side of delay valve.
2. Connect one end of a 24 inch length of rubber hose to vacuum gauge and opposite end to port on white side of valve.
3. Apply a constant vacuum of 10 in. Hg and note the time required for gauge to move from 0 to 8 in. Refer to Fig. 26 for applicable time limits.
4. If defective, replace valve. If original valve is satisfactory, reinstall it with colored side toward vacuum source.