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Idle Mixture: Notes

NOTE: Mixture adjustment is not a normal tune-up procedure. DO NOT remove idle mixture plug unless vehicle fails emissions testing or carburetor has been disassembled.
  1. Set parking brake and block drive wheels. Remove air cleaner for access to carburetor, but keep vacuum hoses connected. Disconnect and plug other hoses, as directed by Emission Control Label. Remove idle mixture needle plug (if equipped).
  2. Place transmission in "P" (auto. trans.) or Neutral (man. trans.). Warm engine to normal operating temperature. Ensure choke is open and A/C is off (if equipped). Connect a tachometer and a vacuum gauge to engine. Check ignition timing and adjust if necessary.
  3. Lightly seat mixture screw and back out 3 turns as a preliminary adjustment. Start engine and adjust idle speed screw to specified idle speed on Emission Control Label. Then adjust idle mixture screw to obtain highest RPM. Repeat both procedures to obtain best idle.
  4. Reset curb idle speed to specification. Remove gauges, unplug and reconnect vacuum hoses and install air cleaner
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