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Thread: exhaust manifold to exhaust pipe connection

  1. #1
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    Default exhaust manifold to exhaust pipe connection

    Hi all,
    I have recently installed a 79 280zx motor into my 71 240z. I tried to bolt the exhaust pipe back up and realized that the 71 exhaust pipe flange is smaller than teh 79 exhaust manifold flange.

    What are my options to connect the two pieces? I've searched and all i've found is that the exhaust shop can fix it. How would a shop fix this? seems like they would need the exhaust pipe from a 280zx in order to fix it.

    Could i get an exhaust pipe from a junkyard and swap it over my 240?

    Considering i'm out of budget and in no rush to finish, what do you z guru's recommend?

    Thanks,
    Ty

  2. #2
    Registered User 240ZX's Avatar
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    Default

    I believe you've answered your own question! Get the correct exhaust connector, remove the old one, weld in the new one, and drive! Or use the old exhaust manifold to replace the 79 unit....but who wants to go smaller?

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    Default

    Thanks 240ZX,
    Since i'm new to working on cars, i like to check my ideas with seasoned veterans.

    the only hang up with welding a new piece on is that i don't have the equipment to weld. I'm sure i can fabricate some sort of connection. Are the diameters of the 79 exhaust pipe and my stock 71 exhaust pipe the same?

    thanks,
    Ty

  4. #4
    Registered User 240ZX's Avatar
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    Quote Originally Posted by tttz
    Thanks 240ZX,
    Since i'm new to working on cars, i like to check my ideas with seasoned veterans.

    the only hang up with welding a new piece on is that i don't have the equipment to weld. I'm sure i can fabricate some sort of connection. Are the diameters of the 79 exhaust pipe and my stock 71 exhaust pipe the same?

    thanks,
    Ty
    Didn't you already say they are different? My advise to you is to take it to a muffler shop, along with the new connector for the 79 manifold and let them install it.

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    Default Thanks

    Thanks again.

    I know that the flanges are different sizes, but i was inquiring about the pipe sizes. But, if the flanges are different, it would make sense that the pipe diameters are different all the way back to the exhaust tip. I guess a little thinking this through and i could have answered my own question again.

    I'll try to find a 79 exhaust pipe and then let a pro take it from there.

    -Ty

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    240ZX,
    Thanks again for the help.

    I've not had time to get to a junkyard for an exhuast pipe, and i'm still out of budget. What would be the performance loss by using the old exhaust manifold (from the L24)? Would there be any other side effects of using the smaller exhaust manifold with the L28?

    I really just want to be able to drive the car around town. Since i have the original needles in the carbs, its not like the engine is going to be putting out L28 power anyway, right? or am i wrong?

    Hopefully when money is less tight i can get the proper manifold and exhaust (or even a header) and upgrade to SM needles.

    thanks,
    Ty

  7. #7
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    Ty,

    The manifold's are not normally interchangeable. Different shaped ports could lead to massive exhaust gas leaks. Granted you could potentially drive the car with a L24 manifold on an L28 but you will not have any luck getting the L24 downpipe attached to the L28 manifold. The angles are not quite the same where the downpipe attaches to the 3 bolt flange. Trust me on this as I've done the swap myself. When I did this swap years ago, I bought a L28 downpipe from Victoria British, then had the exhaust shop connect it to the stock L24 exhaust system. Cheap yet effective. You really have no good options aside from getting the correct combination of parts.

    Chris
    1973 240Z HLS30-156693

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    Default shoot

    oh yeah. I forgot about the port shape issue. Thanks again.
    -Ty

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