Motorcraft 2150 Idle System

How Do You Adjust Idle Mixture?

When rebuilding your 2150 and off the car, screw in the idle mixture screws until gently seated (you can damage the needles if too tight).

Once the carburetor is installed.

  • Warm the engine to operating temperature.
  • Adjust the idle speed to manufactures specifications.
  • Alternate between the two screws.
  • Turn in clockwise 1/4 turn at a time, alternating between screws.
  • Wait until the engine catches up. You will hear it.
  • When the RPM starts to drop.
  • Turn the screw back out 1/4 turn.
  • It is OK to adjust the idle mixture screw back and forth a bit to get a smooth idle.
  • If turning the screw all the way in doesn’t kill the RPM, then you have a carburetor problem.
Updated on 12/27/2020

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