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Which Flywheel For Even 231

Discussion in 'Early CJ5 and CJ6 Tech' started by masscj2a, Jan 16, 2020.

  1. Jan 16, 2020
    masscj2a

    masscj2a Member 2020 Sponsor 2019 Sponsor

    Chester Mass
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    Dec 27, 2013
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    Not sure if this is exactly where to post this tech question, but I'm buying a 231 even fire with fuel injection and electronic dizzy. I'm wondering which is the right flywheel to use in front of my T18 ? I know the 225 odd fire flywheel can be used if professionally ballanced for the motor, but I'm looking for one that was intended for this motor. Any ideas out there ? Thanks in advanced.

    Moderator people, feel free to banish me to time out, or just move this one to the right location please, if I have made the wrong assumptions. (again) :bow:

    FWIW, this motor is going into the Jalopy. Leaving the odd fire on the engine stand for now. Just wanting some EFI love for the old Jalop.
     
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  2. Jan 16, 2020
    Rich M.

    Rich M. Shoe pusher

    Maryland
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    736
    The expensive one from AA, TA Perf or Novak. They are virtually unobtanium otherwise. Due to the low rpm and weight while debateable a neutral balanced 225 flywheel can be gotten away with.

    Edited: personally I think the AA / Novak /TA offerings are McLeod pieces but they are always " out of stock" elsewhere at half the price. McLeod pn 467100-6A
     
    Last edited: Jan 16, 2020
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  3. Jan 16, 2020
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    I'm not sure if I can think of a GM car that used the even-fire 231 that came with a manual transmission. As far as I know, every Regal or Monte Carlo, Grand National/GNX, Olds, Cadillac, etc came with some form of an automatic transmission. I need to research to see if there were marine versions of this engine like that of the 225. Marine engines typically use a manual heavy flywheel vs a flexplate.
    GM did have manual transmissions behind the odd-fire 231's is cars like the Skyhawk and Monza, but even those flywheels are very hard to find today. The 231 odd-fire flywheel is considerably lighter weight than the Jeep 225 version. There were 225 Buick Specials/Skylarks with 3 and 4 speed manual transmissions that I suspect had much lighter weight flywheels than the Jeep version. I still have a manual flywheel on a '75 231 odd-fire I pulled many, many years back. I will pull that flywheel to get part numbers and weigh it just to have that info out there.
    -Donny
     
  4. Jan 16, 2020
    3b a runnin

    3b a runnin Member 2019 Sponsor

    virginia
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    Probably wont help the OP, but will a 225 oddfire flywheel work on a 231 oddfire?
     
  5. Jan 16, 2020
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    I have never swapped a Jeep flywheel on a 231, but I expect that a 225 flywheel will physically bolt onto a 231. Keep in mind, the Jeep flywheel was almost 20lbs heavier. I would, at a minimum, take my 231 internal rotating mass (crank, rods, piston,etc) to a machine shop with my 225 flywheel to have everything balanced.
    Better yet, machine off a bit of that extra weight from the flywheel before you take the parts in for balancing.
    -Donny
     
  6. Jan 16, 2020
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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    My practice - if your not running high RPMs a neutral balance is fine on a 225 OF Flywheel in an EF 231. Ran one that way for years (about 14 before it found another home), and that is also what I'm putting in the '62 build. The 231 EF in it was in my son's '46 with a neutral balance on it for 4 years before he rolled it (second motor that way). It had a T14 behind it at that time, its got a T18 now.

    You can as suggested take the rotating assembly in and have it matched, and I might do that if I had the motor down for a rebuild at the time.

    FWIW - I also have a smaller, lighter flywheel that came behind another 231 I have in the shed mated to a Muncie 4 speed.
     
  7. Jan 17, 2020
    masscj2a

    masscj2a Member 2020 Sponsor 2019 Sponsor

    Chester Mass
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    One of the reasons I have stayed away from the 231, was this one problem. But when this engine came along, I had to try to figure this one out. Right now the engine is mounted behind a 200R4, which is great for PO with a divorced TC, but that's not working in my application in a flattie.
     
  8. Jan 17, 2020
    RATTYFLATTY

    RATTYFLATTY I think you need a little more throttle

    Central MN
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    Wasn't the 231/3.8 offered in the Trans Am with a 5 spd behind it?
     
  9. Jan 17, 2020
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Chev Monza/Buick Skyhawk late ‘77-‘80 used 231 evenfire with manual transmissions. Some ‘80’s El Caminos and Camaro/Firebirds as well.
     
  10. Jan 17, 2020
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    I've got a low-mileage '86 Regal 3.8 in the garage that also had the 200r4. I haven't had the time to research the flywheel yet, but was going to see if I can get an NP435 to bolt up to it.
    -Donny
     

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