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Spark Control Computer Spark Test

  1. Warm engine to normal operating temperature. Set basic timing. Disconnect carburetor switch or unground it. Ensure coolant temperature sensor is connected and working properly.
  2. Remove and plug vacuum hose at vacuum transducer. Connect a vacuum pump to the vacuum transducer and apply 16 in. Hg vacuum. Increase engine speed to 2000 RPM. Timing should be within 4° of specifications. See SPARK ADVANCE TEST SPECIFICATIONS table. If computer fails to obtain settings, replace computer.
SPARK ADVANCE TEST SPECIFICATIONS (1)

Application Computer Part No. (2) Advance
Shelby
Fed. 5226449 38°
Calif. 5226645 36°
All Other Fed. & High Alt. Models
Man. Trans. 5226439 40°
Auto. Trans. 5226433 40°
All Other Calif. Models
Man. Trans. 5226455 40°
Auto. Trans. 5226451 36°
(1) Engine speed of 2000 RPM and 16 in. Hg vacuum applied.
(2) All readings plus or minus 4°. If amount of advance differs from emission label, use label as accurate listing.
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