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Orifice Spark Advance Control: Testing

  1. Inspect hose connections between valve, carburetor and distributor. Replace any hardened or faulty hoses that may allow air leakage.
  2. With engine warmed up, tee a vacuum gauge into hose at OSAC valve leading to distributor.
  3. Set parking brake and run engine at 2000 RPM in NEUTRAL.
  4. Valve is operating properly if a very gradual increase from zero vacuum is observed. About 20 seconds may be required to reach a stabilized level.
  5. If vacuum immediately rises to same level as manifold vacuum, the OSAC valve is not operating properly and must be replaced.
  6. If no increase in vacuum is observed, OSAC valve is defective and must be replaced.
    NOTE: OSAC valve may be by-passed during very hot engine operating temperatures. See Chrysler Corp. Thermal Ignition Control (TIC) Valve.
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