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I figured out my mileage today.. i was better off not knowing

Discussion in 'Chevy Trucks' started by mike reeh, Feb 7, 2001.

  1. mike reeh

    mike reeh Senior Member
    Messages: 114

    77 GMC K20.. 4.10 gears, t350 trans, 33" tires, sb400 all original, 6K lbs with me in it.. I went approx. 95 miles on 14.2 gallons.. do that math, thats 6, yes SIX miles per gallon :( time for a new commuter vehicle, boys. whew. thats harsh.

    i do drive with a lead foot, and up some long grades to get home but come on! just thought id brighten some of you 10-12mpg guys' day up :)

    mike reeh
  2. MTCK

    MTCK Senior Member
    Messages: 346

    OUCH That's about all you can say about that. Do you have disconnect for your front axle? If you drive a lot, that could pay for itself in a hurry. My 10-12 sounds great now. Time to buy a rice rocket and park the beast eh?
  3. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    Im not surprised at all,my stock 89 TBI 350 with OD and 3.73 only gets 11-13 in average driving and im not lead footing it.Ive never hammered it much,since its not exactly a hot rod
  4. 75

    75 PlowSite.com Addict
    Messages: 1,382

    Fuel mileage

    Well, that makes me feel a little better but then again, I'm lucky if I see 10 mpg with mine. (350 gas, T400 (2wd) 4.10 dually, 8,000+ lbs) There's a reason why the old girl gets the summers off! Still, can't complain. The truck will do just about anything except pass a gas station. When I want lots of mpg, I ride the motorcycle - not this time of year though!

    1975 GMC C-35
  5. Smither

    Smither Member
    Messages: 55

    That's makes me feel better too, Mike. I've got a '78 K10 with a 400, 350 tranny, and a 203 transfer case with a part time kit. Even in 2wd, I'm only getting about 9-10. I don't know a whole lot about engines, but as far as I know, the guy who rebuilt the motor put a high rise manifold on it with an Edelbrock 1406 on it (I think). I was told that might have something to do with it. I just heard on the news last nite that gas in the midwest may top $3 a gallon in the summer. I'm either gonna go broke, or park it for the summer.
  6. Jeff's Classics

    Jeff's Classics Member
    Messages: 39

    I have a '76 Suburban with a 454 and TH400, so I think I can top most of you. I typically get about 7 or 8 mpg...thought I got about 13 mpg on the first tank, but I was driving really slowly, like an old woman, to make sure the truck was solid. I am thinking of adding an Edelbrock intake and some headers to try to get a couple mpg.
    Oh well, at least I work in the oil industry, so I can consider it job security....
  7. SummitFarmer

    SummitFarmer Junior Member
    Messages: 5

    I guess I won't complain about my 92 K1500 4x4. She's an extended cab with over 200,000 miles. Weekly round trips to the 9 to 5 of about 335 miles and I get about 15.5 mpg. But it still hurts to pull up to the pump and ring it up to about $32 bucks.
  8. 75

    75 PlowSite.com Addict
    Messages: 1,382

    32 bucks?!?

    32 bucks? That's all? I've seen mine edge close to the $100 mark when she's real thirsty! Of course, I am running 2 tanks @ 20 gallons each and here in my part of Ontario Canada, gas prices are hovering around 75 cents per litre. Since a litre is roughly the equivalent of a quart, the math gets discouraging pretty quickly...But hey! That truck is paid for, has been since the day I bought it back in '86!

    1975 GMC C-35

    PS - another factor in the cost comparison is the fact that the US dollar has been kicking the you-know-what out of ours for a while!

    [Edited by 75 on 02-09-2001 at 01:31 PM]
  9. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    I filled my 89 GMC(35 gallon tank),a 5 gallon gas can for the kids snowmobiles,and the little v-boxes 1/2 gallon tank.62 bucks-ouch.
  10. Chopper Lover

    Chopper Lover Junior Member
    Messages: 21


    You forgot about something very important to you mileage equation...

    Did you figure out how much the odometer was off because of the 33" tires? You may be of by as much as 2 MPG depending on the tire size the speedo is calibrated for.

    As an example, I went from LT245/75R/16's to LT265/75R/16's and lost 4 odometer miles per 100 miles actually traveled. Also my speedo now reads about 62 MPH when I am actually traveling at 65 MPH.

    Just a thought...
  11. mike reeh

    mike reeh Senior Member
    Messages: 114

    ChopperLover that is an excellent point.. I just got my speedo working for the first time and I drove behind my g/fs 99 corolla to test its accuracy.. it was about 3-5mph slow and over a distance of 8.2M (corolla), my truck read 7.9.. so I figured it to be a difference of about 3.6% and I made the appropriate modifications when I calculated the mileage..

    as for changing the speedo gear, I plan to do it very soon.. hopefully the dealer can tell me which gear I need for a NP203 xfer case because I cannot find out online.. I can only find out if its the actual trans gear, not for transfer cases. oh well ttyl

    mike reeh
  12. rdh

    rdh Junior Member
    Messages: 13

    i got out of a speeding ticket. told cop i had new tires put on that could be the reasone i still had the tire bill on dash when i was talking t him ,he looked at my tires and said for me to get speed odometer fix and let me go.
  13. evldsl

    evldsl Junior Member
    Messages: 15

    6.2 diesel mileage

    Not to brag, but my 83 G20 6.2 diesel conversion van with 4:10 axle gets 20 mpg on the highway and high teens in town!
    Cost of diesel down here in FL is a *****, tho. I've seen as high as $1.88/gal! If I shop around, I can find it for as "little" as $1.57/ gal. What the heck is up with that?!