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Carb decision - Rochester, Aisin, or Weber

Discussion in '40- & 55-Series Tech' started by FJ55partsBoise, Feb 7, 2004.

  1. FJ55partsBoise

    FJ55partsBoise

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    I put a new gas tank in my 74 FJ40. Following the tank replacement my FJ40 started running really really rough. No power, sluggish, fire out top of carb on accleration, blowing black soot out of exhaust, and seeming to run very rich. All this told me bad carb. \

    Next step was I rebuilt the POS rochester. Still runs like a POS, very rich etc.

    I can fiddle with Rochester, or I have a decent Aisin that appears to have smog stuff, or buy a new Weber

    Which direction should I go?

    1) This is a used Aisin but somewhat clean. Smog ready?? I have a 73 FJ40 that has no smog stuff. How would this adapt?

    The Aisin appears to have a diagram piece which is smog ready. ( this piece is round with a tiny nipple end to connect a vacuum hose to. There is also one other similar end piece that seems as if it would connect to a vacuum line)

    2) rochester ran well. it is a 2 barrel but I think the float is shot and sinking in gas. When I rebuilt it the float was not included in the NAPA kit. This carb worked well for 2 years but now is a thorn is my a**. Next step is replace the float and hope it works.

    3) weber 38mm. Seems as if very few folks go this route.

    FYi _truck has a rebuilt 2F from the PO who took it to the local Toyota dealer. 4 speed, mini PS, front disk, full cage.

    I want a carb that will last and not be a complete PITA.

    I am open to all suggestions, I just want to get this right the first try.

    Thanks
     
  2. FJ40Dude75

    FJ40Dude75

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    aisin is the only good choice weber suck and rochester is american
     
  3. IDave

    IDave

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    I also vote for the Aisen. You have it, and most likely, it matches your vehicle. Go to the Specter Off Road site and match it to the carbs there, and see if it will fit your 2F without much modification. There are a lot of variations on Aisen carbs, so you want to see what you have to figure out what you may need to do to get it running.

    By the way, I would also wonder about some other things that could be affecting your poor running. Plugged fuel filter, bad fuel pump, plugged fuel line screen at the carb, stuck heatriser, improper timing/bad distributor gearing.
     
  4. FJ55partsBoise

    FJ55partsBoise

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    Ok so how do I tell if this is the right Aisin? I can install it and hope? Or better yet how can I tell if it needs to be rebuilt? I was leaning that way anyway really. I was basically given the carb for next to nothing for finding parts for a buddy outside the U.S.

    What should I pay to rebuild the Aisin? Kit from where?

    Is this going to be a PITA as it has smog stuff on it?

    Thanks
     
  5. rusmannx

    rusmannx

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    HIT IT!
    i'm running a 2 barrel rochester, and i don't really like it at all. my aisen was disregarded back in 75'. i was going to put an aisen back on, but i'm saving for the tbi conversion.
     
  6. Romer

    Romer fatherofdaughterofromer Moderator

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    [quote author=FJ55partsBoise link=board=1;threadid=11186;start=msg101234#msg101234 date=1076212291]

    What should I pay to rebuild the Aisin? Kit from where?


    [/quote]

    If you look at my post: https://forum.ih8mud.com/index.php?board=1;action=display;threadid=11150

    I posted links from SOR and CCOT. There are probably a few others. Dave (IDAVE) has used the SOR and is happy. I was hoping to get a few more opinions on which one is better before I buy my rebuild kit.
     
  7. IDave

    IDave

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    [quote author=FJ55partsBoise link=board=1;threadid=11186;start=msg101234#msg101234 date=1076212291]
    Ok so how do I tell if this is the right Aisin? I can install it and hope? Or better yet how can I tell if it needs to be rebuilt?
    Thanks
    [/quote]

    Can you post a pic?
     
  8. FJ55partsBoise

    FJ55partsBoise

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    IDAVE- Thanks man. Go to the Specter Off Road site and match it to the carbs there, and see if it will fit your 2F without much modification. There are a lot of variations on Aisen carbs, so you want to see what you have to figure out what you may need to do to get it running. Ok will do.

    Plugged fuel line screen at the carb- I already know the fuel line screen at the carb is clear as I reconnected it last night and there is no screen thanks to the PO I think.

    How do I check these items?
    Plugged fuel filter-?
    bad fuel pump?
    stuck heatriser?
    improper timing/bad distributor gearing?

    I also thought I might have fouled the plugs?
     
  9. FJ55partsBoise

    FJ55partsBoise

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  10. FJ55partsBoise

    FJ55partsBoise

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  11. FJ55partsBoise

    FJ55partsBoise

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  12. IDave

    IDave

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    Can't help you much more on the carb. I'd say it is a 69-74 2 Barrel for an F engine. Since you have a 2F, there may be linkage issues, and I don't have experience with 2Fs to tell you how much trouble it would be to adapt. It could be adapted and work well, I believe, but someone else needs to chime in on that.

    I guess since your problem started after you changed your fuel tank, I would first disconnect the fuel line at the carb and point it into a container while someone cranks it for you. Fuel should flow evenly and smoothly. Good place to start for checking fuel filter and pump.
     
  13. FJ55partsBoise

    FJ55partsBoise

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    Thanks Dave- I will try that in the morning. I never messed with the timing or the distributor at all. We will see how the fuel pump and filter works.

    Next step after that I will swap in the Aisin for the F.

    I don't know what a heatriser is but I will start where you suggested.

    Thanks
     
  14. IDave

    IDave

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    Heatriser is the little temperature coil-controlled flapper valve in your exhaust manifold (numbers 62 and 63 in the figure). It directs warm exhaust to the underside of the intake during warmup to improve fuel/vapor ignition in the chambers. It is supposed to close off and redirect to the exhaust pipe when things warm up. If the coil fails, it could lock in the "cold" position which would make for lousy running and some of the problems you are seeing. (Don't ask how I know).
     
  15. FJ55partsBoise

    FJ55partsBoise

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    OK- I checked the heatriser, the fuel pump and the fuel filter. All were O.K. Fuel pumped very strong on cranking with fuel line disconnected

    I checked the Aisin and it appears there is no reasonably easy way this older F style Aisin I have will line up with the linkage setup that I have. I have a real shady tree linkage setup going on. All the linkages I have appear non stock and very shady tree by the previous owner.

    My next step is to replace the float in the rochester and hope that was the problem. I already rebuilt the carb and the float was not included in the kit. I did replace the little brass bullet at the end of the float. I am heading to NAPA now to get the new float(hopefully they will have it).

    If replacing the float doesn't work I am at a serious loss for what to do next. I am not afraid to part with some cash to get this right. My concern is that with the ridiculous style of linkages I may not be able to get a Aisin to work right even if I bought a good one already rebuilt. If I go with the Weber carb are all the linkages included. I can replace parts and troubleshoot but when it comes to designing linkages I am seriously lacking in skills. Suggestions please?
     
  16. IDave

    IDave

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    You can probably just bite the bullet and buy a 2F aisen and the linkage for it, and just sell your aisen. That is what I would probably do. I would probably get one of SOR's rebuilt non-USAs, since you don't need to worry about the anti-smog stuff. I don't have any faith in the Rochester. I think they were put on in the 70s because people were familiar them, and they fit, not because they were any great shietz. And, like Ken Romer said, the webers seem to be tough for a lot of people.

    I think fixing the float is a good idea, but if it doesn't work, I'd get a proper Aisen and buy the linkage. Someone here probably has it in their stockroom in the garage. But that's just me.
     
  17. IDave

    IDave

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    By the way, I was looking at the pictures of your Aisen, and I was wondering if there is a crack at the base of the vacuum nipple on the left side, 2nd pic?
     
  18. FJ55partsBoise

    FJ55partsBoise

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    I thought a new post was in order as now the question is different. I accidentally posted this in the wanted. Sorry Woody

    option 1 - Please see the attached photos of my current situation. I will replace the float first on the rochester and see if it works.

    Option 2- to buy a linkage setup to make my older F style aisin work with the 2F.

    IDave- I checked the Aisin that I have and found no cracks. If I found a complete linkage setup, do you think the Aisin that I have could work on a 2F? My thoughts are if number one fails to rebuild the Aisin I have and source a complete set of linkages? If my Aisin cannot work on this 2f, where other than SOR should I source a correct year Aisin? Will the Aisin I have be an acceptable core to a guy like Jim. C?

    I was completely floored at what SOR wants for a weber. I would have about $600-$700 into it after all the linkages and delivery. That to me is too much
     
  19. IDave

    IDave

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    I have no doubt your aisen would work on your 2F, but I don't have experience, so someone else should chime in. Just get the cable linkage and accellerator pedal for an F (SOR has the whole ball game, or I bet someone here who has done a 350), and you will be good to go.
     
  20. IDave

    IDave

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    Actually, I am looking at your accellerator cable linkage and thinking what you have will work just fine with your aisen.
     
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