Oddfire Flywheel Rebalancing

Discussion in 'Jeep Utility Tech' started by Phalanxx, Sep 11, 2017.

  1. Sep 11, 2017
    Phalanxx

    Phalanxx Jeep Newbie

    iraq, texas,...
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    i think my dad told me i could have the oddfire fly wheel rebalanced and put on an even fire.
    i would like to run the heavy oddfire for crawling.

    i havent spoken to my dad in years. i forgot what i am supposed to do. am i supposed to get it neutral balanced or zero balanced? or do they actually have a measurement for the even fire?

    will this affect by harmonic balancer? will i have to open the engine up and balance the crank?

    thanks in advance guys..
     
  2. Sep 11, 2017
    Phalanxx

    Phalanxx Jeep Newbie

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    never mind. i found my answer. however, novak says both the OF and EF are externally balanced where as everywhere else i look, it says what you guys are saying. of-external, ef-internal.
    ill have my flywheel neutral balanced and use my ha
     
  3. Sep 11, 2017
    Focker

    Focker Rust Never Sleeps Staff Member Sponsor

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    :(
     
  4. Sep 11, 2017
    Dauntless1971

    Dauntless1971 Member

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    This was all I could find appears like you say they are both externally balanced. And not much difference really. Although the location of the weight is not in the exact same place. Unfortunately the photo showing the different location is no longer available.
    G.M. V-6 ODD FIRE
    A : location of weight
    1964-77
    225, 231
    96.5 Counter balance in grams



    G.M. V-6 EVEN FIRE
    C : location of weight
    1977-87
    231
    71.5 Counter balance in grams
     
  5. Sep 13, 2017
    Phalanxx

    Phalanxx Jeep Newbie

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    this is weird. everwhere else but novak says its internally balanced including here.
     
  6. Sep 14, 2017
    tarry99

    tarry99 Member Sponsor

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    Both those motors depend on both external and internal weight to balance them..........as the cranks are totally different...........You'll need to take your complete rotating assembly down to the balance shop to balance & use that heavy 52 lb OF flywheel.........If you have low axle gears and a granny low gear trans.........I would use a standard 30-32 lb flywheel and forget about packing that extra 20 lbs of rotating weight around.
     
  7. Sep 14, 2017
    Daryl

    Daryl Sponsor Sponsor

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    Before the internet told us we couldn't use an OF flywheel on a 231 EF I did it several times. I have never balanced one and have never had one not work. Several others on this site have had horrible results however. It is probably well worth a little effort to get one balanced and do it the right way the first time.
     
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  8. Sep 14, 2017
    wheelie

    wheelie beeg dummy Sponsor

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  9. Sep 14, 2017
    tarry99

    tarry99 Member Sponsor

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    Having an internal balanced motor means that you have enough counter weight on the crankshaft to zero balance the assembly.........on my race motors I order a crankshaft based on my bob weight......Pistons, rings, wrist pins , cir clips , rods , bearings and a little over balance for oil.....the crank is built to that absolute weight (see picture)........and no further balancing is needed unless at a later date the motor is changed to a larger bore or anything else that would upset the bob weight..............

    Externally balanced motors are necessary when the crankshaft does not have enough room or counter weight to satisfy the motors needs for balance ..........then the only choice is to add very expensive heavy metals to the crank or weight to the front hub or flywheel.............

    The Buick Oddfire because of the crank pin sharing two rods on a 6 cylinder motor is a perfect example that needs help externally.............the even fire due to the offset crank pin can probably be internal only if you had the right crankshaft.....


    In either case if your not spinning the motor at high RPM you may get away with the unbalance......but , it might be harder on bearings and seals.

    Auto manufacture engineers determine what is needed when designing and building a motor based on many things like crank shaft stroke , bore , crankcase volume , and use both the internal and external balancing methods when needed.

    [​IMG]
     
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  10. Sep 14, 2017
    duffer

    duffer Rodent Power Sponsor

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    But you forgot the most important aspect of the OEM engineering: COST. It will be designed at the absolute minimum cost still deemed to give a functional result (read: last longer than the warranty). That usually, but not always, leaves something to be desired.

    Your crank is certainly a piece of art, but doubt most of us need anything close to that.
     
  11. Sep 14, 2017
    tarry99

    tarry99 Member Sponsor

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    Didn't think anyone would need one.....................Just a reference John to how many in the racing community go about the crank balancing act.................and Yes cost is why the OEM cranks normally don't have enough counter weight in the middle and therefore rely on both methods of balance , internal and external.........
     
  12. Sep 15, 2017
    Phalanxx

    Phalanxx Jeep Newbie

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    my crank? you mean the grand national steel crank (rolled fillet i was told)? or the oddfire crank thats ruined?
    i have both flywheels. i was thinking about using the oddfire for crawling because my wife and i cant do much jarring and anything we can do to smooth things out would be helpful. so, set the to 1000 rpm, let out the clutch and let the flywheel work.

    thats the train of thought behind it anyway. not a good plan?
     
    Last edited: Sep 15, 2017
  13. Sep 15, 2017
    tarry99

    tarry99 Member Sponsor

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    If you have an even fired motor........you need to stay with an even fired crank and rotating assembly...............as far as crawling along low gears would make more since especially with 33" tires.........using the heavy flywheel is really only temporary Torque Per Se as it really only adds Inertia for a moment.......
     
  14. Sep 15, 2017
    Dauntless1971

    Dauntless1971 Member

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    One right way is what a fellow I worked with would always say. I figure a neutral balance would be no better than no balance at all. If you were to balance the odd fire flywheel it would have to be balanced with the whole engine torn down in a shop.
     
  15. Sep 18, 2017
    Dauntless1971

    Dauntless1971 Member

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    Seems like a new even fire flywheel runs over three hundred.
    Chances of finding a used one is not much better than winning the lottery.
    But here are a few numbers if you do happen to locate a used even fire flywheel.

    [​IMG]
     
  16. Oct 4, 2017
    Keys5a

    Keys5a Sponsor Sponsor

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    Somebody posted an even fire flywheel on RockAuto a few months back for under $100 delivered. You might want to search this one on our site. I think it was listed for a mid-'80s Buick, maybe Grand National or Regal?
    On a related subject, many years ago I worked on a CJ5 with a 225 that the owner had rebuilt including having the rotating mass balanced. I have never seen a 225 that was so smooth running. It had the unique exhaust note, but was as smooth as a V8.
    -Donny
     
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  17. Oct 14, 2017
    Phalanxx

    Phalanxx Jeep Newbie

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    i have an even fire flywheel. bought it for the project years ago. i want to use the odd fire. that extra rotating mass will help with smaller to mid level bumps. i will have my throttle set with a 10 speed derailer at around 1000 rpm. so the odd fire wheel will help with the initial inertia change. itll keep it from dying as easily. especially, if i have to stop on a hill. i can let the clutch out with the throttle set and the mass can get it off from a stop better than a smaller 35 lb flywheel. i got the flywheel/pressure plate/cluth assembly from like a pontiac sun fire or something small. had a 3.8 even fire...good to go.

    i found a guy on the turbo buick site who lives not too far. professional gm mechanic. he is going to help me gather all the pieces and get it in and running. i am pumping it up a bit, but nothing over board so the engine will be disassembled. balance it all as one. that way i can measure everything and see if it needs machined or if i can get by with an over haul/honing job, new oil pump etc. i will just have the flywheel balanced as if it were an even fire. make sure its all good. keep the rpm down..

    but when i asked about the multiple fuel tanks and return lines, he told me corvettes have multiple gas tanks (i dont know anything about vettes). he said they pump from a saddle tank per se' into the main tank as needed. so, since i have my main under seat tank with sending unit and whatnot, ill just set up a pump to go from the 19 gallon rear tank into my smaller one when i am running low. 30 gallons in a fuel injected over drive jeep might get 20 mpg. thats a 600 mile radius give or take. shouldnt have to fill up during the weekend outing (or all the way to colorado..lol)

    thanx for the chart though! with the 4.56 gears, a 79:1 crawl ratio should take me a ton of places. dana 44's with 35's, chromoly and lockers should be plenty tough. nothing too extreme though, i wanna make it back home. this might even become my DD.
     
    Last edited: Oct 14, 2017
  18. Oct 14, 2017
    tarry99

    tarry99 Member Sponsor

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    Keep in mind .....the use of the inertia created by the heavy flywheel is only Momentarily , as the heavy flywheel cannot "add torque" Per Se as the engine does when it creates power. It can only add inertia as it spins and is then loaded. The application of the load to the spinning mass uses that Inertia to increase torque for say a second............after that Kinetic energy is absorbed only the torque of the engine is now available once again. At that moment , the extra mass of a heavy flywheel becomes a liability as it begins to absorb a portion of the engines torque once again to re-accelerate the heavy mass.

    The combination of lower gears and your 79:1 crawl ratio will help mask that transition while off road when in lower ranges.........as your gear multiplication does what it is designed to do Per Se by accelerating mass with minimal penalty.
    The heavy flywheel I believe becomes a greater penalty when driving on road while trying to accelerate without the use of lower gears , especially at freeway speeds trying to accelerate while drag is also a factor.

    I found personally think one or the other ( heavy flywheel vs gears ) works quite well to balance road manners...........with a top speed of say 3 mph+/- in low gear at say 80:1 I can't see where the heavy flywheel would have much effect on inertia compared to the low screws............just my opinion.
     
  19. Oct 24, 2017
    Phalanxx

    Phalanxx Jeep Newbie

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    yes, the heavier flywheel will slow down acc. however, thats what the turbo is for. passing, on ramps and whatever else.. =)
     
  20. Oct 24, 2017
    tarry99

    tarry99 Member Sponsor

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    Good luck on the turbo..........and getting it to spool up that quickly with the heavy flywheel.
     

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