Speedo gear--- getting closer

Discussion in 'U-shift em' started by Sturmgewehr, Apr 16, 2007.

  1. Sturmgewehr

    Sturmgewehr Well-Known Member

    Ok got the WHITE(19 tooth) put in my MUNCIE now @60 MPH only 4mph slow--actual=56.The RED 21 tooth was actually only 49MPH@60mph indicated:eek2:
    Going to get an 18 tooth brown from TCI----my source doesn't have one. :ball:
    ---Thanks Pete My rear is 323 with 28" tall
    BFG radial TAs 275x60x15s. Also @60(actual radar) my tach is reading 2600 to 2700 so it
    is fast by about 300RPM.:af:
     
    Last edited: Apr 17, 2007
    Sturmgewehr, Apr 16, 2007
    #1
  2. Sturmgewehr

    Sturmgewehr Well-Known Member

    Re: Speedo gear-got it right 60=60mph

    Update--BROWN gear 18 tooth, 28" tall 275x15x60 TA radials and 323 rear
    is exactly 60 indicated and on radar.:cool: Tach is still SLOW by 300/400rpm:ball:
    60 should be 2300 reads 2600, 70 reads about 2900 which is closer to 2600.
    I got the MPH/RPM numbers from the late Dove's Book page 253:kodak: ---VERY HANDY
    data--wish I could reproduce it here! Pete
     
    Sturmgewehr, Apr 18, 2007
    #2
  3. Marco

    Marco Well-Known Member

    Re: Speedo gear-got it right 60=60mph

    You mean your tach is reading a higher RPM than the engine is actually turning, correct? My factory tach reads high by about the same amount (about 300 rpm at 3000K on the gauge - I had Rob Chilenski at Stage1 Automotive verify this when he installed the pertronix unit in 1999). At least it reads higher and not the opposite :pp

    Added in edit - the speedometer discrepancy exponentially increases with RPM
    at 750 - it's even
    at 1K reading, the engine is at 900
    at 2k reading, the engine is at 1800
    at 3K reading, the engine is at 2700

    I just shift at 5500 when I'm 'on it' (probably at or below 5K) :3gears:

    There are companies that will recalibrate these (although I don't know any off the top of my head).
     
    Last edited: Apr 19, 2007
    Marco, Apr 19, 2007
    #3
  4. Sturmgewehr

    Sturmgewehr Well-Known Member

    Re: Speedo gear-got it right 60=60mph

    Thanks for the input Marco---good info to
    have. The page from Dove's book with gear ration/mph/rpm and tire diameter
    is really good -wish we could get it STICKIED here for all to use. Pete
    :3gears: +1
     
    Sturmgewehr, Apr 20, 2007
    #4
  5. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    here is the info I used. Worked well. Speedo is almost dead nuts.

    http://www.chevelles.com/shop/speedo.html

    My repo tach is actually dead on, I tested it against the rev limiter and it was spot on. I figure I'm on of like 1000 who actually have a good experience with the repo tach. I even have MSD.
     
    436'd Skylark, Apr 20, 2007
    #5

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