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tuning 2GC carb

Discussion in 'Early CJ5 and CJ6 Tech' started by billybbean, May 2, 2010.

  1. May 2, 2010
    billybbean

    billybbean Member

    Kemmerer, Wyoming
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    On my 225 Dauntless I am running very rich on the left side bank. It idles fine but as you break the throttle open and hold it it starts to spit and sputter blowing and blowing smoke. I've noticed that the manifold is divided in two, left to right. I recently went through the carb, cleaned it all out, new gaskets and such. Near as I can tell I can't find any vaccum leaks.
     
  2. May 2, 2010
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

    cordele, Ga.
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    Re: tunning 2GC carb

    When you open the throttle, do you see two streams of gas (one for each venturi) and they should be a good steady squirt? How far are the idle jets screwed out from the bottom. Should be about 1-1/2 to 2-1/2 +/-. If you have a vacuum gauge, it is a very good tool for this. Is your auto choke open?
     
    Last edited: May 2, 2010
  3. May 2, 2010
    billybbean

    billybbean Member

    Kemmerer, Wyoming
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    Re: tunning 2GC carb

    Lot's of good advice there. Idle jets are 1 1/2 out on both. and the venturies are squirting equaly. I took of the auto choke and riged up a manual. If I choke it about 1/3 it smooths out. I thought this was a timming issue at first. Thanks to all the knoledge on here I "think" I can rule it out. Maybe a bad intake gasket?
     
  4. May 2, 2010
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

    cordele, Ga.
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    Re: tunning 2GC carb

    The exhaust comes up thru that iron base and it takes a while to warm up. Usually the two holes in the intake are carboned shut. Let it run (idle ) for a while until completely warmed up, then check your idle screws with vacuum gauge.
     
  5. May 2, 2010
    billybbean

    billybbean Member

    Kemmerer, Wyoming
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    Re: tunning 2GC carb

    I don't have a vaccum gauge at this time. When I whent through the carb I dug all the carbon out of the base of the carb and manifold. The only idle screw that is making a difference is the right one. I can totaly close the left one and It dosn't make a differece. I can still remove all the plug wires on the left side and it still runs, a little smother even. I know I have good spark at the plugs.
     
  6. May 2, 2010
    billybbean

    billybbean Member

    Kemmerer, Wyoming
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    Re: tunning 2GC carb

    I watched the carb from the top while idling. The venturi on the left side is dribbling fuel (quite a bit actualy) and the one on the right is not. What could cause that?
     
  7. May 2, 2010
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

    cordele, Ga.
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    Re: tunning 2GC carb

    Some carbs have a vacuum hole that sucked heat thru the choke. If this one had it you have to plug it. Are you sure your vacuum advance diaghram is good. That gas dribbling is probably what is killing those three cylinders. You may have a crack in the casting in the air horn assy.
     
  8. May 2, 2010
    billybbean

    billybbean Member

    Kemmerer, Wyoming
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    Re: tunning 2GC carb

    I have the choke vaccum hole pluged. I' pretty sure my air horn is ok. I sprayed carb cleaner around it while running and no difference. How would the vaccum advance diaphram play inyo this? At idle there is no vaccum on it. Maybe a stupid question. I'm trying to learn and figure this out. Thanks for the advice!
     
  9. May 2, 2010
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

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    Since you are running on 3 cyls I think your throttle is open a bit to compensate. This brings the throttle plate up which creates vacuum at the distributor. If the advance is blown then you have vacuum open to atmosphere. Suck on the line from the carb to the advance. If you can't then it is ok. If you can suck air then it has a hole in it.
     
  10. May 3, 2010
    billybbean

    billybbean Member

    Kemmerer, Wyoming
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    Thanks, Walt. My vaccum adv. seems to be ok. While tunning I have the port on the carb plugged. I'll throw this out there tell me what you think. It seems I could have one of two issues here #1 timming #2 vaccum leak. I have timming set to 5 deg BTDCC. I don't see how I have timming off. But if the left side is not firing right wouldn't it cause hire vaccum and try to suck in more fuel? Kind of like a vaccum leak. I am at a loss. I'm sure that the dribbling fuel out of the left side of the carb is definently causing the problem. I just need to figure out WHY!
     
  11. May 4, 2010
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

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    The vacuum is equal throughout the entire manifold so it would effect both sides equally. There is something wrong (appears) in the venturi circuit. Maybe incorrect gasket used blocking air/vacuum passage - the main well tubes not lined up properly (observe flat part of lip goes toward center) or not under gasket - wrong pump discharge ball used (large one for this) and the small one goes under the accelerator pump.
     
  12. May 4, 2010
    billybbean

    billybbean Member

    Kemmerer, Wyoming
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    Walt, if I'm ever in GA I owe you a beer or two! I took the venturies out and cleaned them out again. The smaller tube on the right was basicly plugged. I used some small wire and air and got them all cleaned up. What a difference. She is purring like a kitten. Crazy to think all this just because a little tube was plugged! You gotta love Jeeps or they will make you go crazy! Thanks again!
     
  13. May 4, 2010
    dnb5853

    dnb5853 Member 2019 Sponsor

    SLC, UT
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    I'm glad you got it fixed!
    Don't under estimate the Rochester 2G carb. It was used in allot of vehicles for allot of years.
     
  14. May 4, 2010
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

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    Glad also that you have it going good. Welcome to Ga. anytime.
     

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