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Gas Mileage for 1977 Ford F-250

edited November -1 in Repair and Maintenance
So im thinking about getting a used 1977 Ford F-250, but so far my biggest problem is it's gas mileage. (currently about 7mpg) My question is, how can i improve it, besides just paying for fuel additives, and is there any way i can get it all the way up to somewhere around 15?

Comments

  • edited May 2010
    Which engine and what kind of transmission? Is it a 4x4? How much city driving vs. highway driving? Have you had a tune up lately?

    If that's city driving, it's probably not going to get much better. If it's mostly highway (and you have any motor other than the 460), you should probably be getting a little better, though it may just be a matter of slowing down.

    Assuming the engine is in good tune, the bearings are turning good, the brakes aren't hanging up, etc there's probably not much that'll help the mileage. If you've got a V8 with a 2bbl carb, putting on a sequential 4bbl might help a little (assuming you can keep your foot out of the secondaries).
  • edited May 2010
    it has a 390 engine, manual transmission, 4x4 and pretty much all city driving. to and from school every day, thats about it. it has 38,000 miles on it and has 4 gears plus reverse. im usually driving around 45-50 mph and not stopping for lights either. (early morning lights are usually green)
  • edited May 2010
    Make sure the timing is set correctly..The Motorcraft / Autolite 2V carb has a "power valve" which has a vacuum operated rubber diaphragm. If the rubber diaphragm fails, the valve opens to the "power" (rich) position at all times, destroying gas mileage. But 12 or 13 is all you will ever get but that's a LOT better than 8....

    Your question to your mechanic: Do you know how to rebuild a Motorcraft 2-barrel carb??

    38,000 miles...That's 300 miles a year average...HHHHhhhMMMmmmmmm
  • edited May 2010
    It has actually not really been used much lately and is sitting up at a ranch up in the rockies.

    -thanks for the tip.
  • edited May 2010
    I agree with Caddyman about the timing and the carburetor power valve. The latter is a common problem on aged Ford carburetors anyway.
    Also in agreement that this truck is never going to be a mileage getter even if everything is spot on.

    Many years ago I used to own a Plymouth Roadrunner and a Dodge SuperBee and if driven gently I'd get about 8-10 in town; and by gently I mean driving like there was an egg under the pedal. "Normal" driving would drop it to about 7 and a heavier foot would put it in the 5-6 range. Watching the gas gauge plummet before your eyes hurt a bit but it was fun to do at times.
  • edited May 2010
    I had a 1972 half ton with automatic that got about 14 MPG with a 302. I put a Holley 2 barrel carb on it so I could get more power. It worked. AT and AC were the major options along with PS.

    To get 14, you need a smaller engine or a different truck. The tires (on the good side) may need more pressure. Sometimes you find 35 PSI when it should be at least 55 PSI. Chances are that you will never see anywhere near 10 MPG.

    A car magazine tried to improve fuel economy with a Suburban (about 1977) and did a lot of practical things and got one more mile per gallon. My 454 Suburban got 7.6 MPG, any time of year at any speed. I got rid of it because it took $18 to fill the 30 gallon tank. That kind of money would get you 27 gallons of gasoline in those days.
  • edited May 2010
    The first vehicle I ever had was a 1974 F-100 2WD with a 390 4bbl transplant and 4.11 gears. It never got any better than 9 MPG. 15 MPG isn't happening with a 33 year old F-250 though.
  • edited May 2010
    Your trip length will dictate most of your MPG in that thing. It takes so much fuel to get out of fuel enrichment. That's exclusive of the near 6000lb chassis demanding its due.

    There are too many things that can need refreshing in a 33 year old carb'd engine. Sorting them out will cost more than just buying a beater 30mpg trashed econobox.

  • edited May 2010
    All you can do is make sure the carb is working properly and the truck motor is in tune. In '77 that might mean points, rotor, condensor, and properly setting the ignition timing. I'm not sure if electronic ignition parts were used back in '77? If not, then this truck needs a "tune up" about every 15K miles.

    Since it is an old ranch truck, change the plugs, plug wires, distributor cap, rotor, points (if it has them) and reset the timing to specs. If your mpg doesn't improve there isn't much you can do. To change the truck differentials isn't going to yield enough mpg advantage to pay off for the money and time it will take. The stick shift helps in getting more mpg.

    Just drive it slow and keep a light foot on the gas petal and you might get it up to 10 to 12 mpg if it is running in good tune.
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