big block factory rocker arm ratio

Discussion in 'Engine Topic' started by nuhmizer, Aug 25, 2007.

  1. nuhmizer

    nuhmizer Veteran Member

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    May 18, 2006
    San Diego, CA
    Does anyone know what the stock rocker arm ratio is for a 454? I looked for a set on summitracing.com and they're all 1.7 and a few 1.8's. I though it was 1.5 but is that sbc?
     
  2. BlownBigBlock

    BlownBigBlock Veteran Member Lifetime Gold Member

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    Mar 2, 2000
    Carlisle PA
  3. Damon

    Damon Veteran Member

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    Nov 16, 2000
    Philly area
    Yeah, 1.7 is stock for a big block.
     
  4. nuhmizer

    nuhmizer Veteran Member

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    May 18, 2006
    San Diego, CA
    So if I bought roller tips that were 1.72 ratio, would that drastically change the lift? I have a 560 lift edelbrock cam, stock valve springs.
     
  5. ZS10

    ZS10 Moderator Staff Member Lifetime Gold Member

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    Jan 18, 2003
    BC, Canada
    do the math.
    560 divided by 1.7=cam lift. Cam lift times 1.72 = new valve lift.
     
  6. nuhmizer

    nuhmizer Veteran Member

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    May 18, 2006
    San Diego, CA
    566.58.

    Is that too much for stock valve springs
     
  7. ZS10

    ZS10 Moderator Staff Member Lifetime Gold Member

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    Jan 18, 2003
    BC, Canada
    Depends if they're singles or duals and they're open/closed pressures.
     
  8. nuhmizer

    nuhmizer Veteran Member

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    May 18, 2006
    San Diego, CA
    singles. I dont know what open/closed pressures is. They are just stock valve springs
     
    Last edited: Aug 26, 2007
  9. rustbucket79

    rustbucket79 Veteran Member

    .560 plus stock bbc valve springs equals spring bind/cam death. All the factory springs had far too much spring rate, giving them weak seat pressure and stupid (350#+) open pressure, or simply not enough room for even .500" for the newer stuff. Check your installed height and buy the appropriate single spring.
     
  10. nuhmizer

    nuhmizer Veteran Member

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    May 18, 2006
    San Diego, CA
    Now thats good to know
     

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