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1977-78 Models

  1. Start engine and allow it to reach normal operating temperature. Check and adjust engine idle speed. Disconnect throttle opener control solenoid electrical connector. Connect a vacuum gauge to intake manifold vacuum to check operating pressure.
  2. Run engine under no load and note operating pressure shown on vacuum gauge. Increase engine speed to 3000-3500 RPM, quickly close throttle valve, and note vacuum gauge reading.
  3. Manifold vacuum should quickly increase to at least 24 in. Hg, then gradually decrease to level noted at idle. Operating pressure (vacuum) at idle should be as shown in TOCS OPERATING PRESSURE CHART. See Figure.
  4. To read table, find matching atmospheric pressure on right side of chart. Trace a line following arrow-line "A" to find the correct operating pressure. If altitude is known, find matching altitude at bottom of table. Trace a line following arrow-line "B" to find the correct operating pressure.
  5. If necessary, turn adjusting screw on end of vacuum control valve clockwise to increase pressure and counterclockwise to decrease pressure. See Figure. After each adjustment increase engine RPM and recheck operating pressure.
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