Engine Idle Low When Cold, High When Warm

Discussion in 'Classic Mustang Specific Tech' started by mhjo, Jul 5, 2013.


  1. mhjo

    mhjo Founding Member

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    When I start the car in the morning the idle is very low. After driving moderatly for a while it gets to normal operating rpm. If I drive the car hard and it's a hot day the idle rises way up (1500 rpm)

    This has haunted me for years, and noone has given me an answer to what the problem is.

    The carburator is an Edelbrock 500cfm with electrical choke.
  2. Jake2012

    Jake2012 Member

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    It's possible your carby might have an air leak and is sucking air. Check the main gaskets first and if not, then check the carry itself .
    mhjo likes this.
  3. mhjo

    mhjo Founding Member

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    Yes, we will check this. Thanks.
  4. j69302

    j69302 Active Member

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    Not sure if this can happen on edelbrock carbs, but the fact that you say it idles high after you drive it hard, makes me think the choke is re-engaging the high idle. I would check the adjustment of the choke. It is possible the spring is installed wrong or adjusted far enough out that it re-engages.

    Next time it does this, take the air cleaner off and see if the choke flap is closed.

    Taken from Edelbrocks website:
  5. mhjo

    mhjo Founding Member

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    Thanks, we will check this

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