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  • Carb leak

    It seems the carb is leaking gas on each side. I have the inlet manifold red paint that has been burnt off probably with gas dropping on the hot surface.
    I hope it's clear without picture.
    Is that something often encountered and what is the cure?

  • #2
    Carburetor leaks are very common. When was it last rebuilt? If it hasn't been done recently I would rebuild it and check the condition of the throttle shafts. If they are worn gas will seep through and leak on the intake as you described.

    John
    John Pizzi - Squarebirds Administrator

    Thunderbird Registry #36223
    jopizz@squarebirds.org 856-779-9695

    https://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

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    • #3
      Thank you John
      I have no clue when it has been rebuilt, if ever. It seems clean and in good condition overall. I will ask around how to rebuild it.

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      • #4
        The burnt intake manifolds, at the center section, is due to the exhaust gases that flow through, not usually because of a gas leak. Not to say there isn't a leak, Make sure there is a leak first before doing any kind of remedial work. Every YBlock around has the same problem, which can be remedied easily enough although it entails the removal of the intake.
        Midland Park, NJ
        56 TBird, 54 Ford, 48 Ford,

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        • #5
          How could I check the condition of the throttle shafts and eventually rebuild them?
          Is there some O ring there?

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          • #6
            If there's any movement side to side or up and down then they are worn. There is no o-ring. It's metal to metal contact. If the shafts are worn they need to be replaced.

            John
            John Pizzi - Squarebirds Administrator

            Thunderbird Registry #36223
            jopizz@squarebirds.org 856-779-9695

            https://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

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            • #7
              Or the housing may be worn??
              Can it be fixed?
              Last edited by Eric S; July 10th, 2020, 01:28 PM.

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              • #8
                Depending on the carburetor there may be bushings between the shaft and housing that wear out and can be replaced. You should be able to see if yours has them. If the housing is worn and there's no bushings it can be drilled out and bushings installed.

                John
                Last edited by jopizz; July 10th, 2020, 01:38 PM.
                John Pizzi - Squarebirds Administrator

                Thunderbird Registry #36223
                jopizz@squarebirds.org 856-779-9695

                https://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

                Comment


                • #9
                  I wasn't able to remove the connection on the throttle so I removed the nut. Is it a quick connection easy to remove or does it needs to be unscrewed from the nut?
                  Is the set up seems to be normal? I see that Larry's selling a 9447CR Spacer plate. Do we need it? When? What for?
                  Any link where I can find what is wrong on a carb? Except a potential leak that I would like to check, I would like to check what can be easily checked...
                  But I don't want to fix what ain't broken
                  Attached Files

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                  • #10
                    Your setup looks normal to me. Your carburetor doesn't call for a spacer. Your studs aren't long enough for one anyway. There are a number of videos online about rebuilding the Holley 4000 carburetor which it appears you have.

                    John
                    John Pizzi - Squarebirds Administrator

                    Thunderbird Registry #36223
                    jopizz@squarebirds.org 856-779-9695

                    https://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

                    Comment


                    • #11
                      Well there is some play on the shaft. Too much? Maybe.
                      I also noticed the choke valves are locked but maybe they are locked by the automatic choke system. Secondary valves shows some kind of dark brown sticky stuff and when I manually move them there is a suction/wet noise when the primary open and close with no noise except metal to metal frictions.
                      Also the primary opening has a slightly harder spot.
                      Perhaps once cleaned all these problems will be solved. But are they really problems?
                      Now the question is should I repair it, will I be able to do so with the proper kit, can I have it repaired? If so where?
                      I watched Mike's carburetor parts' videos. Seems easy to reassemble but they do not say anything about checking what may be wrong before disassembling. I don't want to fix something that works.
                      Don't know if Mike's repair or just sell parts...

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                      • #12
                        Been in touch with www.MikesCarb.com

                        The gas at the throttle shaft could be carb flooding/percolation which is common with an overheating problem. Or it could be the shaft/bore is worn, but typically seeing fuel here is because the carb is getting too full and this is the point of least resistance.

                        Generally speaking we wouldn't try to troubleshoot a carb if it wasn't cleaned and rebuilt. We have lost of tech info on the 4000 here
                        https://www.carburetor-parts.com/Hol...al_ep_337.html


                        So I am going to get a repair kit from them and in the time I'll wait for it I will check the float for condition.

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                        • #13
                          Cleaned the engine area a few days ago and although I make a lot of notes, I can't remember where this wire goes
                          Attached Files

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                          • #14
                            I see two wires in your picture. Neither of them look factory. Which one are you talking about. You should only have three wires coming out of a harness near your intake. One is the positive to the coil, one goes to the temp sender and one to the oil sender.

                            John
                            John Pizzi - Squarebirds Administrator

                            Thunderbird Registry #36223
                            jopizz@squarebirds.org 856-779-9695

                            https://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

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                            • #15
                              The long white/yellow in forefront. Connected to a wire from the harness, the other end is the connector with a red part that is in front of sender.
                              hope you see what I mean...

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