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231 even fire balancing

Discussion in 'Early CJ5 and CJ6 Tech' started by rich45, Oct 12, 2003.

  1. Oct 12, 2003
    rich45

    rich45 New Member

    atascadero,Califo...
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    Not that I'm any where near ready to do this,but I've heard two different ways to do this.One balance the evenfire crankshaft for the 225 flywheel and harmonic vibration dampner and Two balance the 225 flywheel for the evenfire crankshaft.I was assuming balancing the crank was the way to go.Which is correct?Proablely clear as mud.The only reason I'm even thinking about this is I have a spare 231 and performance parts seem to be more available for it.I could run a 4 barrel and so on...I really like the 225 but it's in need of rebuilding and I could redo this one and use it once the 225 gives out.
     
  2. Oct 13, 2003
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Any machine shop worth their salt will balance the the flywheel to match the crank. an imbalanced flywheel will create all kinds of vibration and balancing the crank to match the flywheel won't do much to stop that vibration of the flywheel. If you want a truly balanced engine, the rods, pistons, crank, balancer, clutch, flywheel must all be balanced together. If you just want to be able to use the 225 flywheel on a 231 even fire then you can have just the flywheel balanced to the 225 specs. Nickmil.

    OOPS! meant to say flywheel balanced to the 225 specs. :oops: Nickmil.
     
  3. Oct 13, 2003
    michigan_pinstripes

    michigan_pinstripes I'm not lost, I'm wandering

    Clarkston MI...
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    Yes, what he said... balance it all.

    This is a very crucial step on Buick motors vs. a typical chevy V-8 thinking. Rods are commonly off a gram or so and should be corrected.

    I have a bunch of 3.8 links that I am forwarding to Sparky to archive on the site. Very good reading!!

    Do some research on 4-bbl setups. You may hurt low end. A good running 2-bbl and the right cam is plenty for a Jeep gearing. The 4-BBl was installed in those heavy full-size cars to for highway passing.
     
  4. Oct 15, 2003
    rich45

    rich45 New Member

    atascadero,Califo...
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    Thanks guys,I will check out the four barrels-I had heard they may effect torque/low end.I haven't got a real firm grasp on the torque/horsepower thing,don't really understand the different types of intakes either.I do like the two barrel carb/oil bath air cleaner if for nothing else it's simple and works.I may be wrong but doesn't the 231 oil a little better then the 225?
     
  5. Oct 16, 2003
    michigan_pinstripes

    michigan_pinstripes I'm not lost, I'm wandering

    Clarkston MI...
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    As far as HP, a stock 231 should produce between 105 to 115 HP. It is easy to get a 231 to the 150 HP range with a decent carb, cam, and heads. Use 1979-87 "highport" heads. These are standard, common heads and should be easy to find on every 3.8 after 1978.

    Run an aftermarket chrome aircleaner with a K&N to help HP and torque. If you are running a manual gearbox, 150HP will do everything you want in a Jeep. Remember, you are after torque more than HP. At 150 HP, a 231 should produce around 225 ft of torque.

    You should see better oiling results from the 231. The 1980+ blocks are best. Pat's book discusses oiling piculiarities of the Buick.
     
  6. Dec 8, 2007
    durk

    durk Member

    Ontario/Canada
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    Is it possible to simplify the whole balanced 225 oddfire flywheel on a 231 block?? First question is the 231 block internally balanced and the 225 oddfire externally balanced with the flywheel? If the 231 IS internally balanced would that mean any rotating mass ie flywheel or starter ring gear would just be a neutral rotating weight not effecting the balance of the 231s crank. Or does the 225s flywheel just need to be balanced like a car's wheel to make sure its rotating in a true balanced state?? Any info about this whole balancing 231/225flywheel would be most helpful.
    Thanks J
     
    Last edited: Dec 8, 2007
  7. Dec 8, 2007
    StraightToPlaid

    StraightToPlaid Ludicrous speed!!!!

    West Chester, OH
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    Could this all be simplified if you can find the 231 flywheel? Or is there a problem with that.
     
  8. Dec 8, 2007
    durk

    durk Member

    Ontario/Canada
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    You're right stock 231 flywheel would keep things straight forward, but the donor 231 I have was from an auto. Also I'm try to keep the engine swap cheap I just neeed the jeep up and running for winter plowing.
     
  9. Dec 10, 2007
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    The operative word here is if. They can be very hard to find, much more difficult to find than a 225 flywheel as most 231/252's were in front of automatics.... They can be had new but iirc around $250.. Nickmil
     
  10. Dec 10, 2007
    durk

    durk Member

    Ontario/Canada
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    So if the 231 flywheel is somewhat elusive to find, and as well kinda expensive at 250 bucks! How do I mate a 231 to a 225 flywheel???? WHAT has to be balanced to make this combo work??? Does the 225 flywheel have to be balanced neutral, or does it need to have a certain amount of ounce weights added or removed?? Does the 225 flywheel have to be milled to be the same lighter weight of a 231 flywheel?? Someone out there must of been sucessful in this swap, what EXACTLY NEEDS to be balanced. Any input on a sucessful swap or links to other sites would be helpful.
    Thanks J
     
  11. Dec 10, 2007
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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    I have done this a couple times - and both ways. I have an engine that when it was built I took the flywheel down and the machine shop balanced everything to match. I also have a EF 231 with a 225 FW that was balance neutral, and I have a 231 EF with a 225 FW that has had nothing done to it. Both of those work fine, thought the 'balanced' engine is a much higher performing setup.

    Just food for thought - 'what is a balanced engine'... Straight from Pat Ganahl's V6 book:
    'the even-fire Buick reciprocating assembly is considerably underbalanced (36.6%) to reduce vertical engine vibration (while proportionately increasing horizontal vibration)’ - and this is from the factory.

    My take - unless you are building a high RPM motor for performance - close is good enough. Just make sure to use good dampeners on the motor mounts for the vibration.
     
  12. Dec 11, 2007
    durk

    durk Member

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    Alright Warloch... Thanks for the input, though I still have a couple questions?? When you said you had a 225 fw balanced neutral for the 231ef, what exactly did the machinist do to balance the 225 fw neutral for the 231, so I would know?? Though I'm leaning towards your last solution for the 231/225fw just put the combo together NO balancing and a decent set of motor mounts and no high RPMS.
    Thanks J
     
  13. Dec 11, 2007
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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    There is a spec sheet that the machinist looked up on 'how' a 231 is supposed to be balanced from the factory. He matched that for the 'neutral' setup. Beyond that - I couldn't tell you.

    One other thought - some call a neutral balance as the FW spins without any warp or it's 'balanced' like a top. If you do that the engine will have no more vibration than it would just running without anything attached (assuming an internal balanced engine).
     
  14. Dec 11, 2007
    durk

    durk Member

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    Thanks Warlock, if I decide to balance it I'll give the machinist the info. I haven't seen the engine yet its still in the 86 regal at a family members place, just wondering if you knew if the block would still be a mechanical fuel pump? When did the 231 block changed over to an in tank pump??
    Thanks J
    One last question,, will 225 exhaust manifolds bolt up to the 231 heads and did you encounter an other problems with the swap.
    Thanks again
     
  15. Dec 12, 2007
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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    Hard to tell on the fuel pump - the parts books list both electric and mech for that make, model, year. The mech fuel pump is the same for a 231 and 225 other than the fuel line plumming (return or not).

    The exhaust should be fine - the only issues I have had was going the other way - 231 exhaust mans to a 225 as some of them had smaller exhaust ports in the heads.

    FWIW - I have pulled 231s out and put 225s in and visa versa. The only other thing that you may not have thought about is the water pump. The 231s pump is longer (pully is closer to the RAD) than the 225. You may need to be careful with fan clearance.
     
  16. Dec 12, 2007
    durk

    durk Member

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    Alright... your experince in this swap will lead to my wisdom LOL. Thanks for the info, mind me asking how did you deal with the longer w-pump in your past conversion . Does Gm or is there an aftermaket short nose version. ONE more question before I kill this topic, will the 225 carbed intake manifold bolt up to the 231.
    Thanks again
     
  17. Dec 12, 2007
    Toolmaker

    Toolmaker Member

    Westminster, SC
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    Are you sure? When the fuel pump went out on my 225, I pulled the pump from my spare 231 engine (1980 model). The "arm" that rides on the eccentric was shaped differently between the two pumps and I don't think they are interchangable. I *think* the new pump I bought for my 225 even came with a sheet in the box that noted this difference in the "arms" and cautioned against swapping them.
     
  18. Dec 12, 2007
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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    Based on my experience they are the same - at least for the years of the 231 that I have dealt with I should say. Most of the 231s I have worked with are the older (or earlier) models. That would be the only diff I could think of as I have 2 of each in the shop and they are the same.
     
  19. Dec 12, 2007
    Warloch

    Warloch Did you say Flattie??? Staff Member

    Falcon, CO
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    The short nose version is the 225 version - I would NOT recommend swaping the pumps unless you have a full set of pullies to match as the offsets will not mix... Don't ask me how I know :oops:

    There are a couple intakes that will swap and these are after market, but most of the time NO. I believe that '79 was the cutoff for the heads to work together.
     
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