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Another MPG question?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Sparky, Jan 30, 2001.

  1. Sparky

    Sparky 1/2 ton status

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    San Antonio(summer) Texas A and M (school year)
    350 with comp cam 4x4, open element air filter, no emission equipment,q-jet, th350, np203 with part time kit and MM hubs, 33bfg at's, 3.42:1. Only getting 10 mpg at a constant 65mph. Something wrong?

    Sparky

    When all else fails... Check the blinker fluid.
    78 K-5
     
  2. Logan

    Logan Registered Member

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    From what I've seen around here, and from what I've experienced with my own truck, I've got to say that 10 seems to be the magic number for K5's. I've had mine break 14 on a long, flat, 55mph-dead-on run, but anytime I'm playing in the city, or any combination of City/highway driving, I'm back down to 10-12. It's been a bit higher lately, but my clutch is going -- You never realize how often you stomp on the gas until the power stops getting to the ground. ;)

    The fuel-injected boys w/ cruise control have claimed numbers reaching up into the low 20's, but I've never seen anything close to it.

    -Al.
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    Have you done a basic tune up? 33" tires will bring your ratio down to 3.00 if the original tire size was the 235/75R15's...I'd think you might be able to squeeze a couple more out of the truck, but not much...is the tranny stock stall and such? That will hurt MPG as well. But I think others are right, without OD, you aren't going to get into the higher numbers cruising on the freeway.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://yeagerd.home.mindspring.com/index2.html>http://yeagerd.home.mindspring.com/index2.html</A>
     
  4. turbo

    turbo 1/2 ton status

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    A 700R4 with overdrive plus lockup would likly up highway milage to 12 to 15 range.
    The OD lowering RPM plus no more TC slippage with lockup are about all you can do.
    That big front has alot of wind drag at speed.
    A manual tranny without OD would get you about 1/2 the gain and a NV45oo OD manual would do about same as the 700R4.
    A TH400 would drop milage another 10% worse then it is now.
     
  5. UseYourBlinker

    UseYourBlinker 1 ton status

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    That's about what I am getting...
    33's, 3.08, 350, stock tranny...


    <font color=green> No machines are perfect!</font color=green>
     

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