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gas mileage

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 85k5blzr, May 13, 2001.

  1. 85k5blzr

    85k5blzr 1/2 ton status

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    I was wondering how i could get better gas mileage. Just wanted to see if some people could offer up some of their tips and tricks. Right now i have a 350 (HO? because it only runs off super gas) with a quadrajunk (that needs rebuilding i think becuase of the sluggish throttle and how it seems to lose gas when i press the gas pedal). I also have a K&N 5.5" tall round air filter. 32" tires and 3.08s as an added bonus with a 700R4. I have changed the fuel filter, but haven't messed with the electrical systems. I get a little over 8mpg city and 10 highway. Any thoughts....?

    K5 just upgraded to rig status! [​IMG]
     
  2. CaptCrunch

    CaptCrunch 1/2 ton status

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    best bet would be ditch the 3.08 gears... that is what is killing you. A msd coil and some good wires and plugs gapped at .060 would help also

    [​IMG]
    1987 Chevy K5 Blazer- 350 TBI
     
  3. 73Jimmy

    73Jimmy Registered Member

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    The biggest improvement I made to my rig was a Jacob's Ignition, wires and an electronic point/condenser kit. Most of the folks here like the MSD ignition, but I have no experience with MSD. It cost about $500 but
    made a new rig out of my Jimmy. The things starts like a champ and runs like a top.

    I had 31/10.5/15 tires on it to start, and got 10MPG. I have changed the ignition and the tires, now..
    I have a 73 Jimmy with a 350/350/203(still full-time)/3.73/750R16. . My last trip from Portland, Ore to Moscow, Idaho, doing 55-75MPH, I got 13.6MPG. On a previous trip from Yakima, WA to Moscow at a more constant 55-60MPH, I got 14.7MPG.

    If yours is a daily driver, I would get a new High Energy ignition system. You will see the improvement
    right away. If you change rigs, you can move it to your new truck.

    My 2 cents.

    73Jimmy
     
  4. Sparky

    Sparky 1/2 ton status

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    14 mpg with full time on the 203?!?!?!?!?! With my part time 203 same moter tranny and 3.42s in the axles i max out at 12 mpg on the highway and the city is worse. With full time, i was lucky to get ten mpg, but that was with in inefficent engine that has since changed. Either that ignition is the ultimat bad ass or something is wrong somewhere. Never heard of anyone getting that kind of mileage with that setup. Do you have a q jet or something else like a single barrel?

    Sparky

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

    UseYourBlinker 1 ton status

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    What the hell is gas mileage? I get 9 per gal.



    <A target="_blank" HREF=http://community.webshots.com/user/vwryda>http://community.webshots.com/user/vwryda</A>
     
  6. 77GMC15

    77GMC15 1/2 ton status

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    In 4wheeler this month they checked their gas mileage at recomended psi in the tires then at max psi, it was like 5 psi higher, and it was 1 mpg better. Can't wait until next months gas saving tip. Hey, anyone know which month shows off the ten that made TTC?
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    If you haven't done or at least inspected the plugs and wires, and inspected the dist. cap, thats what you should do. My first truck used to run like crud when I bought it. First time I had the hood open on a dark night I could SEE why. I'm getting 15MPG freeway, and thats without some more carb tweaking. You've got something, or a few things, wrong obviously to get that kind of mileage. Ignore anything people say about mileage not being possible. I got 17mpg freeway in my last K5 (tired 305, tired Q-jet, 700R4, and 3.08s) and even without OD, with 3.42's, and a 350 now, I'm getting near that. City is as high as 13.

    Anyone that tells you to accept that kinda mileage is wrong. Your mileage CAN be better. Of course you must take into account terrain, how you drive, motor, etc., but high mileage is possible. On my trip across the country (NC-WA via CA) I averaged the 17MPG, and thats with numerous moutina passes and hilly areas.

    To (possibly) protect myself and my comments, you say that you have to run super unleaded...how bad of an idle does this thing have? Is it a race motor or a low RPM torque monster? Depending on lots of factors, you must REALLY have some high compression to need super unleaded. 9.5:1 is about the highest for 87 octane gas, I'd be surprised if you have anything higher! I'd be checking timing if you are runing the higher octane to cut down on pinging. You may even have the vac. advance hooked up wrong.

    Dorian
    My tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
    No anti-theft measures on your truck? No pity when its stolen
     
  8. MaxCrack

    MaxCrack 1/2 ton status

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    I got better gas milage when I stopped using it as my daily driver. heheh.




    That's because I'm the devil.
     
  9. muddin4fun

    muddin4fun 3/4 ton status

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    I've got a 350 bored .30 with a 600 cfm edelbrock performer and a K&N open air cleaner with headers and true dual 2 1/2" pipe to flowmasters and drive like a bat outta hell ocasionally and get about 10-12 in the city.

    [​IMG]
    <A target="_blank" HREF=http://k5chevyblazer.homestead.com/home.html>http://k5chevyblazer.homestead.com/home.html</A>
     
  10. K5Jimmy

    K5Jimmy 1/2 ton status

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    Mine's a TBI with 4:10's and a 700R....I get 16 easily on the highway runnin' 70-75...around town I'm about 12 or so...I love the sound of Headers, duals, and air gettin' sucked thru a K&N....kinda wigs out the Suv's and rice boys when I chirp second gear......."Getting older is not an option...Growing up is"......JD

    I'm at 10th and Plum....10 miles from nowhere, and Plum out in the sticks....Stuck?...Hell no..I still got some gas left..
     
  11. 85k5blzr

    85k5blzr 1/2 ton status

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    It's doesn't have any special engine in it. How would i go about checking or changing the compression ratio and timing?

    K5 just upgraded to rig status! [​IMG]
     
  12. wayne

    wayne 3/4 ton status

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    If I was worried about gas milage I would not own one. My all stock 89 Jimmy got less then 14 mpg on the highway.

    <A target="_blank" HREF=http://jamonline.homestead.com/fromthegroundupK54x4/89Jimmy.html>http://jamonline.homestead.com/fromthegroundupK54x4/89Jimmy.html</A>
    <font color=blue>Happy Trails<font color=blue>
    <font color=blue>Wayne<font color=blue>
     
  13. thatK30guy

    thatK30guy 1 ton status Premium Member

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    SOOOOO........what the hell is everybody bitchin' about?!??! My 85 K30 with a 454 gets only "5-6" mpg!!! [​IMG] Wanna trade vehicles?!?! [​IMG]

    When In Doubt, Whip It Out!
     
  14. 85k5blzr

    85k5blzr 1/2 ton status

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    any little bit helps though...i mean $50 every two weeks is a little rediculous.

    K5 just upgraded to rig status! [​IMG]
     
  15. Wheels

    Wheels 1/2 ton status

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    Mine went from 6 to 12 when I rebuilt everything. Old motor was really tired. Changed gears (3.08 to 4.10) and dropped to 9. Swapped out the 350/203 for a 700/205 and run 15 on the highway now (on 91 octane pump gas). The engine I built is a low end torquer (10.4:1 comp ratio, flat tops with 64 cc heads). Anything less than 91 and it pings bad. Everything is tuned and the distributor is recurved to match the engine. If I romp and stomp on the pedal, then gas mileage goes south real quick. With 32" tires, gear change will increase rpms slightly at cruise but the engine will not work as hard to maintain them. I would go to 3.73 if it were me. Tuning up the carb and fixing any leaks (air and fuel) will always help. Q-jets are known for the epoxy plugs leaking air and gas and the butterfly rod leaking air from worn out bushings. Check the distributor shaft for wear and any compononents for age. If this is the stock motor, then running super gas to cut down the pinging is an indication that something else is wrong.
     
  16. JunkYardCrawler

    JunkYardCrawler 1/2 ton status

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    i had the same set up on my rig that u do but i have a 4-speed with a granny low. and my gas was not that bad!! but i had an HEI on mine. not sure if you do or not. not sure if that makes a diff. but try rebuilding your carb
     
  17. dyeager535

    dyeager535 1 ton status Premium Member

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    See what I mean about people just accepting poor mileage, even though numerous people have proven that it is not the norm to be getting "bad" mileage on the freeway? If you are in it solely for mileage, and not hot rodding, I think you would probably get over 20 if you spent the money on TPI and had the motor in top shape.

    Dorian
    My tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
    No anti-theft measures on your truck? No pity when its stolen
     
  18. dyeager535

    dyeager535 1 ton status Premium Member

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    I'm not really sure HOW you can test for compresion ratio when it is assembled. I would think a compression check would yield some clues, but with the variable being wear, there is no way you can say that XXX PSI per cylinder means you have X compression ratio I'm pretty sure.

    Seriously, if it is a "stock" motor, then you should be able to run 87 octane with no problem. Check that the vac. advance is hooked up right first of all, because it can advance your timing ALL the time (when there is engine vacuum) if it is hooked up incorrectly, which could lead to pinging. Have you checked timing at all?

    HOw does it start? Does it seem that the starter is kind of "fighting" the motor to start? Too much timing can cause hard starting as well. Backing off the timing is easy to do, but not necessarily the cause of your problem.

    As well, another problem could be sticking mechanical advance weights, which is actually pretty common.
    Just some ideas....

    Dorian
    My tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
    No anti-theft measures on your truck? No pity when its stolen
     
  19. 85k5blzr

    85k5blzr 1/2 ton status

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    It starts right up just fine with the 93. The engine isn't stock, it is newer, but it has a hard time with the 87 octane. It deisels (putters) a lot when i turn it off and doesn't like to start up with it. When it starts up, it runs a really high idle. I could not even press the gas and the thing will accelerate up to 25 - 30 mph from 0. I can't give you an rpm range because there isn't a tach in the truck. Also what is pinging and knocking?

    K5 just upgraded to rig status! [​IMG]
     
  20. 85k5blzr

    85k5blzr 1/2 ton status

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    THANKS FOR THE ADVICE EVERYONE!
    -sorry, just not too familiar with the engines

    K5 just upgraded to rig status! [​IMG]
     

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