Speed Controlled Spark: Testing: Notes
- With engine at normal operating temperature, ignition timing and idle speed set to specifications, connect a vacuum gauge between distributor advance unit and vacuum hose. With engine at idle speed observe vacuum gauge. If vacuum reading is low (0-2 in. Hg), disconnect hose from high or low temperature vacuum control valve at "T" fitting between carburetor port and distributor vacuum advance unit hose. Plug open "T" fitting, engine timing should increase and vacuum gauge should read approximately full manifold vacuum. If it does not, inspect vacuum unit, vacuum hoses and carburetor for plugging or damage. Reconnect temperature control vacuum hose to "T" fitting.
Courtesy of NOT AVAILABLE
Courtesy of NOT AVAILABLE
Courtesy of NOT AVAILABLE
- If vacuum is still low after preceding test, place both rear wheels on floor stands so they may be spun freely. With transmission in second gear (auto, trans, in "2"), operate vehicle (spin wheels) under light acceleration while observing vacuum gauge and speedometer. At 34±2 MPH vacuum gauge reading should increase from zero to show engine manifold vacuum. Allow vehicle to decelerate (throttle closed), vacuum gauge should drop to zero at 25±3 MPH. If these events occur, system is functioning properly. If manifold vacuum cannot be obtained at any speed, first check for leaking vacuum hoses. Then check for faulty solenoid valve, speed sensor or electrical circuit. Repeat test after any repairs to verify correct operation. If solenoid valve operation occurs at speeds other than those specified, replace speed sensor.
- If vacuum reading is high (approximately full manifold vacuum) with engine at idle speed, shut off engine and check for restrictions in air bleed hoses or faulty operation of solenoid valve, low or high temperature vacuum control valves.