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Gas Mileage? 700R4? New Rear End Gears? I NEED HELP!!!!!!!!!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by andrewvcherry, Sep 4, 2000.

  1. andrewvcherry

    andrewvcherry Newbie

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    What should a 1972 K-5 Blazer with a 350 Engine and Trans be getting. I am getting 6.5 miles to the gallon. I know these are not economy vehicles, but this seems a little ridiculous. Anyone out there have a beast with a 700R4 or any add on that is getting them some better mileage on the road. I want to keep by my blazer, but with gas prices like this if I do not figure something out I am in real trouble
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I have an 81 Jimmy, 4 Speed manual, 350 with an Edelbrock 4 barrel, headers and dual Flowmasters. I also have 35" mudders and 3.73 gears. I consistently get 13.5 to 14.5 Miles per U.S. Gallon. I get 8.5 to 9.5 Miles per U.S. gallon towing my 5300 lb trailer.

    You don't need fancy computers and overdrive to get good mileage (but it helps). When was your last tune-up? Carb rebuild? Tranny service? What kind of gears/tire size do you have? How hard do you drive it?

    I found with mine that I get way better gas mileage if I stay somewhere around the speed limit (These things move a lot of air)

    Good luck

    [​IMG]
     
  3. Chili 87 K5

    Chili 87 K5 Registered Member

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    Yup, I've got an '87 K5 with the 350 (Throttle-body injected) and 700R4, and before the crank went bad, I was getting at least 11 mpg in short-trip driving... and that was with some old and cruddy emissions components.

    I concur; go for the tune and timing, check for vaccuum leaks and front hubs that are engaged! No offense, but I've done waaaaay lamer things myself!

    Brian 'Chili' G.
     
  4. tom

    tom 1/2 ton status

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    Be careful calculating your mileage. Many blazers with gear or tire changes don't give the right mileage on the odometer. Find a piece of highway with mile markers and run it 10 miles or so and see if your odometer agrees. If not, make a simple math correction when you figure your mileage. My '91, 350, TBI, SM465 4 speed, 3.73 gears and 33's gets 16 mgp (highway) if I use the actual odometer reading, but when correceted for the odometer error the mileage is only 14.5 Of course the correction can go either way, you might be getting better mileage than you think. If your odometer is calibrated for smaller tires, then with big tires you actually go farther with each revolution of the wheel, so the odometer shows lower than actual mileage. Check it out.
     

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