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My 225 Fix It Or Scrap It

Discussion in 'Early CJ5 and CJ6 Tech' started by 3rdgenjeeper, Jun 16, 2016.

  1. Jun 16, 2016
    3rdgenjeeper

    3rdgenjeeper Member

    Charleston sc
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    Jun 16, 2016
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    First, I couldn't believe my eyes when I found this forum... you guys are awesome!!!

    Ok boys here's the situation, my block is currently 50 over and the walls are still pitted from where the water sat in the cylinders for a decade or so due to the previous owners negligence. My heart is telling me to go 60 over slam some new pistons and rings in there, button her back up and drive a smokey jeep while I look for a doner motor. BUT every other instinct is telling me I either need to sleeve those cylinders or just be patient.
     
  2. Jun 16, 2016
    homersdog

    homersdog Tulsa, Ok 2020 Sponsor 2019 Sponsor

    Tulsa, OK
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    Jan 8, 2012
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    Welcome from Oklahoma! Tell us more about your jeep. Give us some pics!

    Will .06 clean up the pitting? How much are you going to spend on a temporary motor?
     
  3. Jun 16, 2016
    uncamonkey

    uncamonkey Member

    Greeley CO
    Joined:
    Jun 2, 2009
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    2,104
    You seem to know which way to go with your motor. I believe I read you can go to 0.80 over on a 225 or a L head but you need to see if the cylinder walls can take it.
    Sorry, I assumed you had a 225. My L head was bored 0.60 over shaved. planed and would out run a F head. It would be nice if you gave us a bit more information.
    Anyway, welcome and I hope we can help you.
    Ask questions. We have everybody from shade tree mechanics to people that build race cars here. Somebody can give you an answer.
     
  4. Jun 16, 2016
    3rdgenjeeper

    3rdgenjeeper Member

    Charleston sc
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    Jun 16, 2016
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    60
    A little background on the jeep... the title is currently somewhere in dmv purgatory (had to get it reissued) so I brought the engine home to get cracking one something. The guy I got it from already pulled the motor down and had the heads and block checked by our local machine shop. They poked it 50 over and that's when the po threw in the towel and basically gave it to me for what he owed the shop.

    Now a little about me... I am not a machinist but I do have my own hobby shop (wells/index knee mill, 12 inch clausing, miller syncrowave 300) and overboring/sleeving is well within my comfort zone... so this cuts down the costs tremendously (except for the money I spent to buy all the machines...said my wife...) and I do enjoy tinkering in my shop on stuff like this.

    The jeep itself has good bones but it's gonna look like it dragged itself out of the scrap yard for a while... but I can't embarrass my neighbors and ruin the neighborhood without a beating heart between the fenders.
     
  5. Jun 16, 2016
    3rdgenjeeper

    3rdgenjeeper Member

    Charleston sc
    Joined:
    Jun 16, 2016
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    My current inclination is to do it roadkill style and just over bore, lap the valves, and bolt it back together. Then revisit the subject when it has a catastrophic failure. Anyone think I could go 80 over? That would definitely clean everything up

    Also... the pictures will have to wait, I won't be home again until Saturday
     
  6. Jun 17, 2016
    SFaulken

    SFaulken Member

    Renton, WA
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    May 24, 2011
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    646
    As I understand it .080 overbore is well within the capability of most 225 blocks. Pistons just might get pricey.
     
  7. Jun 17, 2016
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    Ok - 231 pistons already have a 0.050 larger bore than a 225, so there should be a ready supply of larger bore pistons like 70 or 80 over (ie 231 20s or 30s). At larger than 60, I would sonic check the block to make sure the core shift allows the larger bore. Not expensive. Sleeves are going to cost ca $100 per hole, likely more. Only appropriate for an exotic block ... NOT worth it for a common engine like the 225 or 231 - definitely find another core rather than sleeve.

    NB - you say you can sleeve it yourself ... maybe, but you'll still need to source the sleeves and new pistons. Still seems like the wrong approach compared to going oversized.
     
    Last edited: Jun 17, 2016
  8. Jun 17, 2016
    3rdgenjeeper

    3rdgenjeeper Member

    Charleston sc
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    Jun 16, 2016
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    alrighty then... wheres the best/least expensive place for a set of 60 over pistons... or does anyone have a set they'd be willing to part with?
     
  9. Jun 17, 2016
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    Cheap at RockAuto - go to 1977 Buick Skylark 231 cid. 20 over will be a 70 over for the 225. Since you have 50 over pistons now, you probably have standard size 231 pistons already. These pistons fit a lot of GM cars, which makes them cheap to buy. Less than $150 for the set of 231 20s, and $350 for 225 60 over. 70 over should be ok, although I would sonic check anyway. Conventional Detroit gray iron blocks should go 30 over twice, ie 30 and 60, without issue.

    The odd-fire 231 is the 225 after it was taken back from AMC by GM. The bore was enlarged by 50 to unify it with the 350 V8, which was on the same assembly line (according to my sources).

    Note I have only read about this, I have not done it. But as a machinist, you should be able to examine the Sealed Power specs and check that the 231 pistons will work.
     
    Last edited: Jun 17, 2016
  10. Jun 18, 2016
    tarry99

    tarry99 Member

    Northern California
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    Different compression ratio between the 225 & 231 motors
     
  11. Jun 18, 2016
    3rdgenjeeper

    3rdgenjeeper Member

    Charleston sc
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    Tarry, isn't that just a function of a larger bore with the same stroke?
     
  12. Jun 18, 2016
    Rich M.

    Rich M. Shoe pusher

    Maryland
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    736
    Iirc the of 231 has lower compression than the 225. Its been a long time since my 231 was built but I clearly recall getting 350 pistons to bring the compression up ( 69 I believe)
     
  13. Jun 18, 2016
    eti engineer

    eti engineer Member

    Great Central...
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    Jan 24, 2015
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    Unca,

    How far did you shave the head on your L-head? I was thinking of shaving the head on my F-head, but can't seem to find if this is possible and if so, how much can be removed? Thanks...
     
  14. Jun 18, 2016
    3rdgenjeeper

    3rdgenjeeper Member

    Charleston sc
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    Here's a pic of one of the bad holes #3 for those who care
     

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  15. Jun 18, 2016
    3rdgenjeeper

    3rdgenjeeper Member

    Charleston sc
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    Annnnnnnnd all the other parts...
     

    Attached Files:

  16. Jun 19, 2016
    uncamonkey

    uncamonkey Member

    Greeley CO
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    Its hard to say what was done to the motor before we got the Jeep. As we had to go to 0.60 oversized pistons, It had to have been worked on before and who knows what they may have had machined off. I just had them take off enough to true up the surfaces. You probably need to find an old engine guy who can actually identify what a L head or a F head is and would know how much you can take off. IIRC the FSM for my MB had a section on figuring the piston to head dimensions to figure what is allowable. WTH, I did that motor about 46 years ago. You should be able to take off several thousanths.
     
    eti engineer likes this.
  17. Jun 20, 2016
    eti engineer

    eti engineer Member

    Great Central...
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    I will research this and see what I can come up with. With only a 6.9:1 compression ratio, one would think that I would have some wiggle room. Just don't want to get to the point I am blowing things apart and that I have to run 91 octane or better in it. I once had an engine with 11.2:1 compression in it and had to run 103 octane in it, but back then that gas was 23 cents a gallon and went down to 18 cents a gallon when gas wars were on. Those were the good ol' days when lead kept detonation temps high enough one could use pump gas on high compression engines and we didn't have valve recession...
     
  18. Jun 20, 2016
    uncamonkey

    uncamonkey Member

    Greeley CO
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    Sorry I can't tell you more. I only went to 9.5 to one on my bike. The guy that did my heads and such did his step sons Harley to 10.5 to one. It will kill about anything in Wisconsin. My bike would kill about anything here in Colorado. Toms old Suziki would kill about any bike I ever saw. He won't even ride it anymore.
    Tom did my heads and valves, full race setup. As far as I know, he still gets stuff sent to him from across the country to do his magic.
    Tom is also a very realistic person. when he lived here he had an old flat bottom tin tub style of boat with a 6 HP Evenrude on the back. I asked why he didn't perk up the motor. Meh, I'm out fishin' How fast do I need to go?
     
    Last edited: Jun 20, 2016

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