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even fire vs odd fire

Discussion in 'The Hokey Ass Message Board' started by Tiger II, Aug 12, 2008.

  1. Tiger II
    Joined:
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    Location:
    Shenandoah Valley Virginia

    Tiger II Member

    So a discussion came up regarding odd and even fire. Supposedly the Viper V10 is odd fire and the Ford Triton V10 is even fire. Any of you smart folks out there explain the difference.

    Thanks
  2. btbsandman
    Joined:
    Mar 15, 2007
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    Location:
    Mid Central Missouri

    btbsandman Member

    Well I have the 198 V6 oddfire Baby Nailhead in my 1962 Buick. The oddfire has more "rumble" that can be felt in the car when idling at a stoplight. It has a more throaty sound from the exhaust.

    I took this from a Buick Board that describes the oddfire issue in the V6...

    "The firing interval that proved best was every 150 and 90 degrees for each crankshaft throw with a cylinder firing order of 1-6-5-4-3-2, alternating between the cylinder banks. "That was a little bit different than people were accustomed to, and if you sat in the car at idle you had a kind of little dance that you went through, so we said it had a personality of its own."

    I have no clue about the evenfire stuff....
  3. GMC BUBBA
    Joined:
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    Speedway, IN

    GMC BUBBA Member

    Simply put the even fire engine fire in even degrees of crankcase rotation etc. The odd fire engine are uneven spaced firing events.
    Chevy and buick both made some odd fire engine over the years as well , the odd fires ran ok but were a little rough at idle.
  4. Relic Stew
    Joined:
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    Wisconsin

    Relic Stew Member

    Kind of Depends on the angle of the V of the block. V8's are even at 90°, V6 and V12 are even at 60°. When a V6 is based on a V8 block, they are 90°, so they are odd-fire, unless the crank has the pins offset to make it even. Both the V-10's mentioned are 90° blocks, Ford uses offset crank pins, Dodge does not.

    Here is an even fire 90° V6 crank. Funky stuff going on with journal offset.

    [​IMG]
    Last edited: Aug 12, 2008
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  5. bryan6902
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    Crystal, MN

    bryan6902 Member

    Chrysler/Dodge ran the 3.9L v6 which is an odd fire engine for years, actually until 2003 I think in Dakota pick-ups. Just did training for Chrysler cam in block engines and they mention nothing about odd firing engines on the new Viper 8.4L. It does have variable valve timing though, which is insanely awesome in it's simplicity. Kinda makes me angry none of us thought of it first.
  6. hotroddon
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    Orange, So Cal

    hotroddon Member

    Since you asked about V-10's
    The Viper uses common crank pins which creates a 54 degree -90 degree firing order as that's when the pistons come up due to the common crank throws, hence ODD Fire.
    The Ford uses split crank pins that bring the pistons up every 72 degrees, hence EVEN fire.
    At least that's how I understand it.
    Last edited: Aug 12, 2008
  7. no55mad
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    nipomo, ca

    no55mad
    ALLIANCE MEMBER

    As said above, with the Buick V6's, the odd fires had two rods on one crank journal like the V8's. The even fire V6's had a seperate crank journal for each rod.
  8. RAG66
    Joined:
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    WASHINGTON

    RAG66 Member

    Oh man,
    You guys on here scare the crap out of me with all the smart thinking & tech knowledge! Great stuff I didn't know I needed to know!:cool:
  9. BeatnikPirate
    Joined:
    May 21, 2006
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    Location:
    Media, Pa.

    BeatnikPirate Member

    I dug up this old thread because the new "Street Rodder" mag has an artical on a 32 Ford modified with an "Indy inspired" odd-fire V6.
    It says that AJ Foyt and others used Buick and Chevy powered race cars using an odd fire arrangement to create lots of horsepower.
    The artical says that ,with the odd-fire design "groups of two cylinders are separated by 90 degrees of rotation (like in most v8 engines) with other groups separated by 150 degrees of rotation (it's 1-6-5-4-3-2 firing patern requires 720 degrees of crank rotation for all cylinders to fire)."
    I don't get it. Does this really produce more power? If so, can someone please explain how this is and how come more engines aren't set up this way? :confused: Thanks
  10. r759ca
    Joined:
    Dec 23, 2008
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    Location:
    nor cal

    r759ca Member

    i could be wrong but seems to me all motors take 720 degrees of rotation to fire all cylinders
  11. r759ca
    Joined:
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    Location:
    nor cal

    r759ca Member

    oops edit that, that is unless they are two stroke engines
  12. rq375
    Joined:
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    Washington

    rq375 Member

    The other issue is strength, common rod journal (odd fire) cranks are stronger
  13. cheap-n-dirty
    Joined:
    Jan 28, 2002
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    Location:
    fruitland, idaho

    cheap-n-dirty Member

    Here is my 259 inch 1979 Buick even fire v5. it was the protype for the Indy and nascar stage 2 motors. it had 1.88 inch intakes and made 350 hoesepower on gas. it also has a dry sump oil s[​IMG]ystem. the lower end is good for over 8000 rpms.

    Attached Files:

    Last edited by a moderator: Jun 1, 2014

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