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Technical Your RPMs at 70mph

Discussion in 'The Hokey Ass Message Board' started by T&A Flathead, Mar 6, 2017.

  1. flatout51
    Joined: Jul 26, 2006
    Posts: 996

    flatout51
    Member

    Tim likes this.
  2. T&A Flathead
    Joined: Apr 28, 2007
    Posts: 1,818

    T&A Flathead
    Member

  3. cheap-n-dirty
    Joined: Jan 28, 2002
    Posts: 759

    cheap-n-dirty
    Member

    300 hp 327, 2650 rpm at 70mph with 31.5" rear tires in 32 roadster. it like this very much.
     
    osage orange likes this.
  4. Tim
    Joined: Mar 2, 2001
    Posts: 11,784

    Tim
    Member
    from Raytown Mo

    Some without corn in it this time ;)
     
    osage orange likes this.
  5. flatout51
    Joined: Jul 26, 2006
    Posts: 996

    flatout51
    Member

    Sending unit is bad... I hope...

    Sent from my SM-N900P using The H.A.M.B. mobile app
     
    osage orange likes this.
  6. I find the method that works best for me is to not run a tach, then drive as fast as I want and "trust" the rpms are right about where they need to be.
     
  7. Road Runner
    Joined: Feb 7, 2007
    Posts: 1,257

    Road Runner
    Member

    Daily Drivers with 235 and 261 Chevy 6s since 1995 and close to 200K miles total.
    3-speed with torque-tube into 3.55 rear
    Around 3000 rpm at 70 mph and 20 mpg
    3000 lbs. car and truck.
    Water temp at 185 degrees at the most even in the hottest triple-digit summer days in the CA Mojave desert, driving all day.
     
  8. My avatar running a '40 flattie, 5-speed with .8 5th gear, 235/85-R16 " rear tires (almost 32" tall), 3:54 banjo rear - 2350 rpm @70 MPH .... sorry - I just reread your post looking for guys running a 3 speeds ....
     
  9. 911 steve
    Joined: Nov 29, 2012
    Posts: 603

    911 steve
    Member
    from nebraska

    I fall into the category the poster didnt want to hear from, but looking for some input. I have a 40 Ford sedan, stock Camaro 305HO except for a Holley 4bbl, 700R4, 2.79 gears in a Plym 8-3/4 rear end, 235-70-15 BFG's on the rear. I get 21 mpg at 1900rpm at 70 mph, to test it last summer I ran 82mph at 2200 rpm for a 200 mile stretch....still got 21 mpg. a friend says I should change to a 3.73 ratio & get better mileage, but I am afraid to screw with it & maybe get worse mpg. opinions????
    2016-04-26 00.54.26.jpg
     
  10. ago
    Joined: Oct 12, 2005
    Posts: 2,199

    ago
    Member
    from pgh. pa.

    Nice avatar Steve.
    Lower ratio would increase rpms. maybe a compromise would be 3:23.
     
  11. buikwag
    Joined: Apr 21, 2005
    Posts: 472

    buikwag
    Member
    1. Buick Nailheads

    2000 RPM @ 70 with my 401 and 700R4 OD trans and 3:55 Ford rear gears.
     
    jeffd1988 likes this.
  12. seb fontana
    Joined: Sep 1, 2005
    Posts: 6,713

    seb fontana
    Member
    from ct

    Make a test run with trans down one gear and see what the milage is and if the engine noise is tolerable?
     
    911 steve and Just Gary like this.
  13. leroux
    Joined: Jan 29, 2008
    Posts: 309

    leroux
    Member
    from SoCAl

    39 zephyr 3 speed behind my 39 flathead. 26-2800 65-70. 3000 @75


    Sent from my iPhone using The H.A.M.B. mobile app
     
  14. 911 steve
    Joined: Nov 29, 2012
    Posts: 603

    911 steve
    Member
    from nebraska

    yes, she is.....fitness model Jordan Carver.....google her
     
  15. For YEARS, before those new fangled OD transmissions came out, we would build our Hi Performance street cars at almost 2:1 set up, maybe closer to 2.25. We drove everywhere that way - daily driver, long trips, hell it was usually our only cars. So 70 = 3100-3300 rpm range and I put hundreds of thousands of miles on my Hot Rods that way. Just weren't willing to give up the stop light acceleration for lower RPM's on the highway, never even considered it.
     

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