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carburetor questions

Discussion in '40- & 55-Series Tech' started by rodan, Mar 21, 2004.

  1. rodan

    rodan

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    I recently purchased my 72fj40 and so far all I have done is straighten out other peoples messes on this thing. Anyway I have never had it running correctly. When I purchased it I knew the engine was sick, so I rebuilt it. Now that the rebuild is done I am still having some carburetor problems. The idle mixture screw does nothing. You can turn it in or out all the way and it runs the same. The carb has been rebuilt and jetted to the manual specs. Although the thing runs good it is still not quite right. I would like some opinions on what to do. I give up on the original carb (it is a 9/72 build date, and I believe a California vehicle). I don't know what is wrong with it, but I can't find anything. So here is the question. Should I track down another original carb, go with a Holley, or a Weber??? The engine has a "RV" cam ( a little more duration I am told) and a header and a GM HEI distributor. Other than that it is stock. Any suggestions are welcome. Got anything you would like to sell? let me know. ???
     
  2. IDave

    IDave

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    Can't claim true expertise, but if your idle mixture screw truely isn't doing anything, I would suspect 1) your timing is way off. 2) Your screw tip is broken and stuck in the passageway. 3) The passageway is clogged with some other junk.


    I am a strong believer that the concensis is the Aisen carb is the best carb overall for for this vehicle. If a different brand carb solves your problem, then this one was dirty or broken otherwise.
     
  3. Romer

    Romer fatherofdaughterofromer Moderator

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    You might take it somewhere that you can get comfortable with their "expertize" over the phone. This could be a lot cheaper than buying a new one. They may tell you it just needs a rebuild and then there are several option for that. They may tell you your just missing a crew or linkage and fix it right there. I have read several places where people who switched to Holleys or Webers switched back.
     
  4. Pin_Head

    Pin_Head

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    If the engine runs with the idle mix screw all the way in, then the carb may be leaking gas internally because the needle is supposted to be able to shut the fuel all the way off. It may have been improperly rebuilt.
     
  5. rodan

    rodan

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    There is nowhere around here that I would take my Cruiser. The carb has been rebuilt. I did the rebuild and from what the manual showed me there was plenty of things wrong with the way it was when I took it apart. I am convince that this carb is just not ever going to work right. I am not opposed to putting the original type back on, I just give up on the one I have. Also finding the original type might be fun. So if anyone has suggestions on where to find a good stock one I am all ears!
    Thanks,
    Ray
     
  6. rodan

    rodan

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    Pin_head, I think you are right. But I can't find anything wrong with it so I guess I am after another one. ?????
     
  7. Romer

    Romer fatherofdaughterofromer Moderator

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    I know Jim C has the best reputation for rebuilds. Maybe he would take yours as a core trade?
     
  8. hammerhead

    hammerhead

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    If it has a fuel cutoff valve make sure it is functioning properly. If it isn't working the idle circuit is getting no fuel. Be sure you have power at the electrical connection to the solenoid on the side of the carb. Test the solenoid by connecting a jumper from the battery. Most make a click loud enough to hear if quiet enough in the shop.
     
  9. rodan

    rodan

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    I emailed Jim C and I got no reply. Maybe he is on Vacation or something. As for the shutoff valve, just unhook it while the engine is running, it dies right now! So I guess it is working.
    Ray
     
  10. hammerhead

    hammerhead

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    Yep.

    The pilot or idle circuit is the smallest circuit in the carb and the hardest to get clean. A few months ago I had a customer bring in a carb with the same prob. Said he had taken it to three other mechs with no luck. A few squirts of carb spray found the plugged circuit and a small piece of wire plucked from a wire brush opened the passage enough to let the carb cleaner do the rest.

    The broken mixture screw is also a possibility. I've seen that before.
     
  11. IDave

    IDave

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    I broke a mixture screw myself once. It doesn't do anything without the pin on the end!
     
  12. Degnol

    Degnol

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    I've got a '74 California emissions carb, chem dipped, with a new kit in it. I want $85 plus shipping, and if it doesn't work for you, send it back for a refund. Assume you have cable linkage?
    Let me know if you are interested,
    Aun2th@aol.com
    Ed Long
     
  13. cruzer

    cruzer

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    rodan-

    I had a very similar problem with my carb...it would not tune...no matter what i could screw the idle mixture screw all the way in and it would still run..then i could take it out and nothing...i tried cleaning and rebuilding the carb 2 times...gave up and bought a used carb...it worked 100 times better than the old carb...i would suggest sending your carb to Jim C...if he can't make it run correctly no one can...also i emailed him once and it took a long time for him to get back to me. May i suggest calling him...probably a better method of getting ahold of him.


    Stew
     
  14. Pin_Head

    Pin_Head

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    [quote author=rodan link=board=1;threadid=13491;start=msg124826#msg124826 date=1079917735]
    I emailed Jim C and I got no reply. Maybe he is on Vacation or something. As for the shutoff valve, just unhook it while the engine is running, it dies right now! So I guess it is working.
    Ray
    [/quote]

    If it dies when you disconnect the solenoid valve, then it isn't leaking internally at idle. Running rich at idle isn't a big deal unless you have to pass smog. It shouldn't make it idle poorly; in fact it will idle great. When it is lean it won't idle well. What are the symptoms you are worried about?
     
  15. swank60

    swank60

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    I've gone through the same sort of headache recently...kept tinkering with the carb and got nothing...but for me, the rough running and weird stuff was from other systems. Check all of your vac lines, check your PCV (if you have one) check your valve clearance and check your timing. I made a lot of assumptions working on my truck (oh, I'm sure the timing's fine...) and spent a lot of time, effort and money where I probably didn't absolutly have to.

    Most of the time I've spent on my truck, like you, has been fixing crap that the PO had done to it. Don't assume that, as whomever worked on it in the past, put the vac lines back in the right place, or that they took care of the valves or ANY of that other stuff. It's a pain, and there's no quick fix. There are two types of mechanics out there: one throws new parts at a vehicle until something sticks, and the other spends time going over things, asking questions and really looking at what is happening - lots of investigation. You really have to be more of the second type with these trucks - much to my horror - but, as you get familiar with it, it's okay.
     
  16. sl33py

    sl33py

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    OK, Everyone is always talking about Jim C. How do you get ahold of him? I emailed what i think is his email address, but haven't had any reply. Do you guys know any additional info? website? phone number? I am pretty positive that i need a carb rebuild, what does he charge, what kind of turn around? possible cross-ship or something like that if he has correct one in already rebuilt? Thanks for the info.

    rob
     
  17. Degnol

    Degnol

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    What year? E>74 do it yourself. 75> JimC. Be patient, he has always answered my emails. I have a '74 and Jim told me to do it myself, even pointed out the right kit. That and advice from PinHead gave me the strength and courage to do it myself....with good results.
    Ed ;)
     
  18. rodan

    rodan

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    Just to give everyone an update, I purchased a rebuilt carb from one of the forum members. I managed to put it on the other night. I have no problems what so ever with the way it runs now. It has a lot more power than before. The idle mixture worked fine. I think I just had a carb that was junk and that was all there was to that. Anyway thanks for the response to my questions.
    Ray
     
  19. Dunbar

    Dunbar

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    What Ed said. Jim only checks his email at night but can usually be reached by phone unless he is under a rig. Do a google search on "Jim Chenoweth" and you will see some interesting stuff. Including this photo that reveals how he is able to get so much done: http://www.rallyvw.com/jimbio.htm

    Dunbar
     
  20. Degnol

    Degnol

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    Bet there's a BIG fight when it comes to monkey-spankin' time!
    I usually settle mine with a coin toss, but that wouldn't work for Jim.
    ;)
    Thanks for the link, it is always fun to put a face with a name.
    Ed
    And he has always been very generous with advice and time with me and I've never spent a nickel with him...yet.