Rocker Arm Ratio

Discussion in 'Engine, Fuel and Exhaust' started by 92FXSTS, Mar 16, 2010.

  1. 92FXSTS

    92FXSTS Member

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    I'm new to H-D EVO eng mods and was wondering if there are rocker arms with different ratios? Using different ratio rockers is an easy way to help performance on both Chev SB & BB engines and wondered if EVO's had the same options available. Thanks for any info
     
  2. Breeze3at

    Breeze3at Well-Known Member

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    I think Baisley and S&S make 1.7 ratio rocker arms. Jesell V twin makes other ratios as well (or used to). I'm not sure if they are for stock valve train set-ups. Mostly I think the big engine drag racers use them to compensate for altitude, temp. and other conditions (quicker than changing cams). A google search should turn something up.
     
    Last edited: Mar 16, 2010
  3. 92FXSTS

    92FXSTS Member

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    Thanks for the info, I'll do some googling now that I have a direction to go.

    Something I forgot to ask above, do you or anyone know the ratio for the stock arms? Thanks again :)
     
  4. prodrag1320

    prodrag1320 Account Removed

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    remember,when changing r. ratio`s,you must recalculate & check valve to valve and valve to piston.i would run stock ratio rockers,only time we use higher ratio rockers is when a larger cam isnt avaliable
     
  5. 92FXSTS

    92FXSTS Member

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    Thanks for that info, I'm use to doing that 8 times in a row on Chev SB & BB's. Do you know the stock Harley ratio? Thanks for the help
     
  6. Breeze3at

    Breeze3at Well-Known Member

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    1:6 jumped into my head (evo) when I read your last request. The ratio is carried to 3 decimal places .625?, not positive. I'll look it up later if I remember.
     
  7. FishHunter

    FishHunter Active Member

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    OEM rocker ratios are 1.625.
    Scott
     
  8. 92FXSTS

    92FXSTS Member

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    Once again, thanks for the info. I finally took some time to check around, with the info you had already given, and found a few different manufacturers.


    FishHunter, Thanks for the follow-up info.
     
  9. FishHunter

    FishHunter Active Member

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    Happy to try to help.:D
    Scott
     
  10. prodrag1320

    prodrag1320 Account Removed

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    you a fisherman scott? you ever get down to indiana,ill take ya out on my NITRO (of corse) 150hp bass boat,very good bass fishing around here!!