Rebuilt Amc 304 Fuel Issue

Discussion in 'Intermediate CJ-5 and CJ-6 Tech' started by B-Rad, Nov 22, 2017.

  1. Nov 22, 2017
    B-Rad

    B-Rad New Member

    Dayton
    Joined:
    Jun 14, 2017
    Messages:
    34
    Hey everyone, So my Jeep is finally up and running ok after a full rebuild. I even took my carb to a reputable carb shop for a rebuild and going over. I Am a noob at adjusting carbs but am trying to get it figure out. It s a holley 4 barrel 650 cfm I believe.

    I installed a digital stand alone AFR gauge to check my air to fuel.

    At idle its a bit rich at startup and gets closer to 14.7 to 1 when its warmed up. Runs good in first gear even at harder accel, 2nd gear if you really get into it it starts getting lean, and in 3rd if you get on it, it stumbles and the afr gauge goes way lean, pretty much fall on its face, almost to far for the gauge to read. But if you kind of accel sort of hard in steps it doesnt lean out.

    So am I not getting enough fuel volume to the carb? Maybe a new fuel pump? The gas tank and sender are all new, I blew the lines out, and installed a new filter. Could it be ignition related? I am thinking not, more fuel.
     
  2. Nov 23, 2017
    timgr

    timgr Jeepin' Nerd Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    18,208
    Direct the fuel pump output into a jar, disconnect the coil and crank the engine to test output. Careful of fire. A factory fuel pump can deliver fuel at a rate many times higher than your engine needs, even at wide open throttle. The TSM also has a pressure spec for the output that you can measure with an inexpensive vacuum gauge.

    For tuning the Holley, I suggest you get a book and learn about tuning them. They are not hard to adjust, but I'm not an expert, and there's much more to it than we can cover here. https://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias=aps&field-keywords=holley+carburetor+book

    The TSM may help you for setting the ignition timing. Do you have the original ignition? There is a diagnosis guide in the TSM. Probably won't tell you simple things like how to use a timing light... there's likely a YouTube video that walks you through that if needed.
     
    Last edited: Nov 23, 2017
  3. Nov 23, 2017
    4wealn

    4wealn Member

    Ontario, Canada
    Joined:
    Nov 15, 2013
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    115
    When my Jeep was carbureted, I used a vacuum gauge to set the mixture. It worked really well.
     
    58 willys likes this.
  4. Nov 25, 2017
    B-Rad

    B-Rad New Member

    Dayton
    Joined:
    Jun 14, 2017
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    34
    Did you put the vacuum line where the vac advance is hooked to? A friend road with me and said to jet it up a couple of sizes, if you get into the secondaries it richens right up. So I ordered a jet kit and am waiting on it.
     
  5. Nov 25, 2017
    4wealn

    4wealn Member

    Ontario, Canada
    Joined:
    Nov 15, 2013
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    The gauge should be connected to manifold vacuum. Then lean or richen the mixture until you get the most vacuum reading, then reset the idle and do the same for the other side.
     
  6. Nov 26, 2017
    colojeepguy

    colojeepguy Colorado Springs Sponsor

    At the foot of...
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    If he's getting 14.7 at idle then the mixture screws are set ok.
    Do you know what power valve is in this carb?
     
  7. Nov 26, 2017
    4wealn

    4wealn Member

    Ontario, Canada
    Joined:
    Nov 15, 2013
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    I am sorry, I do not
     

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