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2.5l Swap.. Smog Issue

Discussion in 'Intermediate CJ-5 and CJ-6 Tech' started by Paul G, Jul 6, 2018.

  1. Jul 6, 2018
    Paul G

    Paul G New Member

    N CA.
    Joined:
    Jul 6, 2018
    Messages:
    3
    Im looking at buying a 1979 Cj5 with a 304 that has no smog equipment on it. Living in CA that is an issue. I suspect the engine is toast and rather find a reasonable solution. Will a mid 80s CJ7 2.5l drivetrain fit in the CJ5? With most of the smog stuff this may be my likeliest solution. I'd like to assume the engine fits but I'd need different mounts. Not sure on rest re: length. or ability to use current trans/transfer case. Appreciate your input. (Or I obviously buy a pre 75.) Dont plan on much off road sompower isnt a consideration.
     
  2. Jul 6, 2018
    jpflat2a

    jpflat2a what's that noise?

    Riverside CA
    Joined:
    Jul 30, 2003
    Messages:
    7,630
    Maybe easier to find that 80's CJ5/CJ7 with that drive train already in it ?
     
  3. Jul 6, 2018
    dane71

    dane71 New Member

    USA
    Joined:
    May 11, 2017
    Messages:
    25
    I'd consider a howell efi kit if I were you. Look into it but I'm pretty sure that kit was approved to run without the smog pump, thermostatic air cleaner, etc. That efi kit or a pre 76 Jeep are your best options IMO. It's a shame that they have all these hoops to jump through instead of simply basing the emissions test on real world numbers (sniffer test).
     
  4. Jul 6, 2018
    Paul G

    Paul G New Member

    N CA.
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    Jul 6, 2018
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    3
    EFI kit makes sense if the engine wasnt toast which I believe it is. $1500/efi vs $100 on a whole 2.5l w/drivtrain makes it hard to pass up. But yes, a pre 75 makes more sense with all the unknowns and lack of knowledge or input from others.
     
  5. Jul 7, 2018
    dane71

    dane71 New Member

    USA
    Joined:
    May 11, 2017
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    25
    I can't believe I missed that part :rofl:that does change things. From what I just read you would need to find out for sure what year the engine is as there were 2 different 4 bangers used in that decade. The transmission and transfer case already in the 79 are stronger (especially the transmission) so you might as well stick with those but I'm not sure if that works out with smog regulations. You wouldn't be able to use the current transmission and transfer case if it's the earlier 80s iron duke engine, at least without an adapter. I'm not sure if the later 4 cylinder would bolt up to the current transmission in the 79 or not.
     
  6. Jul 7, 2018
    timgr

    timgr Jeepin' Nerd Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    19,058
    A '79 with a 304 will have a 3-speed T-150 transmission, which is a Ford 3-speed passenger car transmission made by Tremac for Jeep under license. Dana 20 transfer case. The 4-cylinder Jeeps had 4-speeds or 5-speeds because they needed the extra gears to help compensate for the lack of power. They also typically had deeper axle ratios, like 4.10s. If you drop a 4 cylinder in to replace a 304, you likely will have disappointing performance, since a 304 probably has 3.54 axle gears. The '80s Jeep will have the superior Dana 300 transfer case, so there's that in its favor.

    I recall the 151 and the 150 have the Chevy V8 bell pattern and Chevy 60 degree V6 pattern, respectively. So they won't bolt up to the exisiting '79 bell. They may work if you modify their bell to work with the '79 transmission, but again - 3-speed, 3.54 axles will be a dog with a 4-cylinder.

    The '79 could have a T-18 truck 4-speed and/or 4.10 axles, but if that's the case, it's a rare combo and very much worthwhile bringing back to factory condition.

    So, if you did this, your best bet would be to put everything from the 4-cylinder Jeep under the '79 - engine, transmission, transfer case, axles.

    My understanding - these '80s 4 cylinder Jeeps usually come with the light duty SR4 or T-4 transmission, which is their main liability. I hear they not only are not very strong, but they also are not durable. Your $100 drive train may run fine, but still need $1000 of repairs. Also, I think these transmissions are not simple to rebuild like the Borg-Warner 3-speeds (or the T-150). The 4.10 axles from a 4-cyl are valuable on their own, and should add significantly to your $100 drive train purchase price.

    Have you seen under the hood of an '80s 4 cylinder CJ-5? As I recall, the engine is more than a foot back from the radiator and there is a very long fan shroud. You'd need to get all these parts that are specific to the 4 cylinder.

    I would also investigate how much trouble I'd have getting a vehicle approved with a newer drive train. Even if it's allowed by the law, you may have to document all your changes and go before a referee. I suspect the law is written to discourage such casual conversions... how much is your time worth?
     
    Last edited: Jul 7, 2018
  7. Jul 7, 2018
    Paul G

    Paul G New Member

    N CA.
    Joined:
    Jul 6, 2018
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    Good points, Thanks ... more research needed. Nothing else from the 80s CJ is available except the engine, transmission and transfer case. Will investigate the 79 a little more but at a minimum the engine needs a rebuild and then a CA Howell FI system install. May decide on pre 75 after all.
     

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