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Stock Exhaust Man With An Offy Intake?

Discussion in 'Intermediate CJ-5/6/7/8' started by Iandavidh, Feb 23, 2021.

  1. Feb 23, 2021
    Iandavidh

    Iandavidh Member

    California
    Joined:
    Sep 24, 2018
    Messages:
    398
    Quick question. In the process of rebuilding my 73 CJ5 and I am getting around to the engine(258). Right now it has a set of leaky headers and an offenhauser intake manifold. For the time being, would I be able to run a stock exhaust manifold with the offy intake while I save up for a really good set of headers?

    Thanks!
     
  2. Feb 23, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    Depends on the design of the intake manifold. In 1973 these manifolds bolted together at the preheater flange that uses exhaust gas to heat the intake manifold. If your intake has the flange, it should work. However, I would worry that the exhaust will be in direct contact with the aluminum intake manifold, and the intake manifold may not last. Also, the flange on these aluminum manifolds were sometimes cut away to clear the headers. If this was done, it will never work with the factory exhaust manifold.

    What might work better is the factory manifold from a '81 or newer 258. This is an iron manifold that does away with the bolt-together flange, intended to be used with the factory aluminum 2V intake manifold. These are the manifolds that I am running on my J10. They bolt up just like the iron manifolds, though I needed to notch the power steering bracket slightly for clearance.
    1983 JEEP CJ5 4.2L 258cid L6 Exhaust Manifold | RockAuto
     
  3. Feb 23, 2021
    Iandavidh

    Iandavidh Member

    California
    Joined:
    Sep 24, 2018
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    398
    Oh I totally forgot that the manifolds were different! Yeah I was looking at the 81 and up 258 manifold
     
  4. Feb 23, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    Yeah, it should work. You may have to mess with the bridging washers some, if the flanges don't meet or are different thicknesses. The factory manifold bolts up otherwise.
     
  5. Feb 23, 2021
    Iandavidh

    Iandavidh Member

    California
    Joined:
    Sep 24, 2018
    Messages:
    398
    Awesome thank you for your help!
     
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