Carter Bbd leaking throttle body

Discussion in 'Fuel and Air Systems' started by harrytoes, Dec 2, 2018.

  1. harrytoes

    harrytoes Well-Known Member

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    My carter bbd is leaking from the from the throttle body linkage. Its the original carb on the 318 in my 68 fastback. Is there a bushing that can be replaced on the shaft?
     
  2. Slantsix64

    Slantsix64 Well-Known Member

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    yes its leaking from the throttle shaft bushing. it can be rebushed. but from my experience i would just tell you to save up and slap a 4 barrel on it 500 cfm edelbrock. better carb easy tuning and can achieve good mileage. the performer intake by eddy is great but the lb4d intake is best for a 318. and if you want best mileage and torque i would recommend the sp2p intake.
     
  3. AJ/FormS

    AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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    If it leaks there while running, something is wrong.
    If it leaks there with the engine shut off, something different may be wrong.
    Fix what is wrong, and it won't leak fuel there any more.
    On a 318,I have never had a problem to compensate for an air leak there.

    There's nothing wrong with the 4bbl idea either as long as you also install dual exhaust with it, and a new timing chain kit. Cuz if you have a 4bbl, you are gonna use it. And with 2.76s, redline in first gear is about 50mph,lol, and if things don't go well up there and the engine has the later nylon tipped upper timing sprocket, then she could rip all the teeth off right then and there...... and that will cost you more than just the tow.
     
    Last edited: Dec 2, 2018
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    • harrytoes

      harrytoes Well-Known Member

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      My dad is the original owner and it’s still all stock. I wanna keep it that way so Im trying to stick with the carter. I actually have an aluminum intake and a performer to go on but I was trying to keep the original one.
       
    • harrytoes

      harrytoes Well-Known Member

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      It’s leaking when the engine is shut off. What could that mean?
       
    • AJ/FormS

      AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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      It means there is fuel leaking onto the top of the throttle plates, or it is boiling off the manifold floor and condensing when it hits the plates.
      One of three things;
      1) percolation
      2) too high a float level
      3) faulty parts, or gaskets.

      If it does not leak while idling, and the engine idles nice at standard timing and carb settings; that probably rules out #2 and #3.

      If after you shut it off it takes more than a minute to appear, then it is probably coming up from the bottom. That would point to evaporation off the manifold floor, which would point to any of the three.
      If it appears instantly, that points to #2, or maybe possibly #3

      If the choke takes a long time to come off, and the electrical choke element heater is proved to be OK, then the heat crossover under the carb may be plugged; this is a common thing on older engines.Or it may be that the heat-riser valve is seized shut. So check the valve and if it is free, pull the intake and chisel out the carbon. The carbon in there acts as a big heat sink,cooking the carb.
      If you pull the intake, you will also need to clean out the chamber underneath it, which requires you to remove the tin splash shield, by removing the rivets which hold it on. That baffle is usually jammed up with carbon as well.
      This presents a bit of a problem in how to reattach it afterwards; cuz if the rivets fall out during operation. who knows what kind of damage that might cause.
      Up here in the North, we have to have that crossover-system operating in winter, for driveability. In San Diego IDK. If you see temps below freezing there on a regular basis, I would leave it operational. On a stock 318, that manifold heater can be very beneficial.
      Ok so
      Pop the air cleaner top and with the engine idling, stare down the carb with a flashlite. You should see dry plates and no dripping. While you are there,kill the engine by pulling the blue wire off the ballast resistor, and continue to stare down the bores, at least a minute. You should not see any liquid dripping nor forming on the plates nor any smoke. This rules out #2, and probably #3.
      After time is up, disconnect the accelerator pump link-arm by pulling the clip and set the rod asside, then start her up again and let her idle for half a minute to burn off the squirt. Then shut her off and open the throttle wide open and fix them there. Then immediately check the manifold floor for liquid with your flashlite. There should not be any on a fully warmed up engine. Then wait about a minute. There should not be any liquid or smoking. If you get either, badaboom there is your source.
       
    • 67Dart273

      67Dart273 Well-Known Member

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      AJ is right. I've seen some pretty loose bushings that don't leak fuel. If the float level is correct, the fuel pressure is not too high, and the needle is properly sealing, AND if heat perculation is not an issue, they won't leak. When running, engine vacuum "sucks" any leakage "in" and they don't leak when running, either.

      When these bushings get bad enough, rather than a fuel leak, unstable idle speed/ idle quality is usually the bigger issue
       
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      • Tooljunkie

        Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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        Is this a case of residue on intake below carb?
        Not a case of fuel actually leaking out?
        I have come across worn throttle shaft bores,but they were whopped right out, but not leaking. Other than them drooling a little leaving traces on the intake.
         
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