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Improving Mileage

Discussion in 'The Garage' started by Snowman1000, May 3, 2007.

  1. Snowman1000

    Snowman1000 1/2 ton status

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    Alright I have a 75 K-5 Carbuerated 350 with a th350 Trans and stock everything else and I need to find a way to get some better gas mileage. 9-10 mpg and now its playin DD duty because my heep blew a headgasket and my other truck (S-10) is on the way (still paintin). Also what causes a truck to "Diesel" when you shut it off (loose ground??? timing???)
     
  2. dremu

    dremu Officious Thread Derailer Premium Member

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    Dieseling can be caused by carbon deposits, from running hot, but is more often caused by timing and/or too high an idle.

    The easiest way to improve mileage on your truck is to drive a Honda. Anything else will not be as cost effective nor simple.

    -- A
     
  3. sled_dog

    sled_dog 1 ton status

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    I'd check ignition timing first. Thats the most likely cause of dieseling. Could be carbon buildup in the chambers, in that case, sucks to be you.

    Best way to improve mileage? Get your S10 back ASAP!

    With a non-overdrive trans, carburated engine, you are doing as good as I would anticipate you would at best. My 84 got like 8mpg most of the time.
    Diesel conversion and an overdrive transmission will be your best fuel mileage mods to that rig. With doing both of them, and the right axle gearing, you'd be over 20mpg easily.
     
  4. Randy92782

    Randy92782 1 ton status

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    i got closer to 12 mpg on the highway but i also had a 305. not sure that made too much of a difference. you could always look into one of those tornado thjings. lol as for the dieseling i'd second the timing issue
     
  5. BigBurban350

    BigBurban350 1/2 ton status

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    Hey man, my ol' Suburban got 12 mpg running a TBI unit. Maybe you can put a new carb on and also make sure everything else is okay. Timing is a good thing (maybe a cap/rotor). Tune up and get everything tip top.

    Drive slower then 70 mph (anything over is a waste of energy). I'm currently looking into water injection...supposed to improve gas mileage on the highway cruise and it keeps your engine cleaner.
     
  6. vortec

    vortec 1/2 ton status

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    on older engines, carbon buildup and the associated hotspotting is pretty common. i use mmo and/or fuel system cleaner (dirt cheap at walmart) periodically. some people dump a little bit of deisel into the tank since it's a good solvent and breaks up the grime and carbon. from what i've seen, it works very well in the right proportion. add too much and the engine stumbles and runs like crap.

    bad timing and vac leaks are the other things i'd look for.
     
  7. sunnyc123abc

    sunnyc123abc 1/2 ton status

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    Water injection? Do you have a link for more info?
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Water injection was used way back in WW2 for airplane engines. They didn't have the technology we have now, IIRC it helped prevent detonation on supercharged engines in thin air (altitude). Still crops up once in awhile, it would be immensely more popular if it actually worked better than what we have already available.

    A better approach is to change the induction and engine designs (bore, stroke, combustion chamber design, plug angle, etc) which is what has been done with the LS series motors, Vortec heads, fuel injection, computer controlled timing, and so on.
     
    Last edited: May 3, 2007
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Swap in a diesel...that'll about double your mileage.

    Rene
     
  10. Randy92782

    Randy92782 1 ton status

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    good answer!!!
     
  11. 79k54life

    79k54life Registered Member

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    Free up that exhaust and get try keep your foot light. The first is easier.

    79k54life
     
    Last edited by a moderator: May 8, 2007
  12. ZJumper

    ZJumper Registered Member

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    Check your tire pressure and front end alignment. It tire pressure is low, it's gonna help empty your wallet quicker. I was running 30psi and bumped it up to 35 and picked up 1mpg. Same with the front end alignment...my alignment was out (toed in too far) had it aligned to spec and picked up 1mpg.
     
  13. Snowman1000

    Snowman1000 1/2 ton status

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    I dont think that it would be a carbon buildup I thought that I would have cleaned it out in the year or so I have been driving it. It doesnt do it every time I would say 4-5 times out of ten it will do that. as for the gas mileage I am going to run a better exhaust this summer one I get some funds. How do you check the timing on this truck??
     
  14. 4by4bygod

    4by4bygod 1/2 ton status

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    carbon buildup, water injection, and fuel mileage

    Snowman..

    You can get carbon buildup every time the cylinder fires.. the initial quality of the fuel's composition has a lot to do with that ,as well as the trucks abilty to efficiently consume the fuel. that's where the timing & exhaust come in.. Since you are carbureted, maybe you are just flowing too much fuel to begin with.

    I will let our esteemed panel of technical gurus explain how to check the timing, air / fuel ratio and carb jetting.. ( paging Dorian )

    Additionally, some folks like to squirt water down the carb or dump in something like seafoam to reduce carbon build up.. the thing to remember with those methods is that they only dissolve the carbon that hasn't been impregnated yet by combustion temps.. what's needed is a high level of continuous detergency to clean out the impregnated carbon over time and prevent the buildup in the first place.

    If you combine combustion efficiency with detergency, better mileage is the by - product.

    Regarding water injection

    According to this website http://better-mileage.com/water1.html , the benefits of water injection are as follows:
    • [FONT=Arial, Helvetica, sans-serif][/FONT][FONT=Arial, Helvetica, sans-serif]
    • Prolongs engine life by controlling heat.
    • Allows for improved fuel economy by running leaner mixtures.
    • Keeps the cylinders and pistons clean by continuously steam cleaning.
    • Helps prevent pinging by cleaning away carbon deposits and cooling the combustion process.
    • Reduces oxides of nitrogen pollutants by reducing the temperature.[/FONT]
    I would like to take this opportunity to point out that rather than go through the hassle and expense of these systems, Our fuel catalysts do all of this and more by simply pouring it in the tank.

    When you get your truck mechanically straightened out, poke around the websites linked in my sig and see if what we are doing has any interest for you..
     
  15. Snowman1000

    Snowman1000 1/2 ton status

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    Alrighty to my esteemed panel of gurus how do I know what to set my carb at check/ set timing let me know anything I need to know to get this motor runnin better. I think I am going to try and put a little seafoam in the engine and clean it out and perhaps next oil change a little bit of oil with a detergent in it. I know my engine is dirty and could use an all around tune up(perhaps a peice of Orbit gum gum down th intake will clean it up). How do you get spark plugs out that have been in there a while worried about breaking them off.
     
  16. sled_dog

    sled_dog 1 ton status

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    All oils have detergents in them unless otherwise noted. And its not common to find Detergent Free oils.
     
  17. ryan22re

    ryan22re 1/2 ton status

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    Penetraing oil on the spark plugs. I have always been partial to replacing a 1/2 qt of oil with tranny fluid every few oil changes to keep things nice and clean. Maybe go 1 qt on the first cleaning, but don't leave it in there too long if the engine is fairly dirty. And if the engine is really gummed up inside, then maybe a commercial oil douche.
     
  18. Snowman1000

    Snowman1000 1/2 ton status

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    So you put tranny fluid in your oil and theres no problems with that how long do you leave it in for. I have been driving it quite a bit in the last few days and have been putting alot of fresh gas through it and it seems to have cleared alot of it up. Its not really gummed up it just sat for quite a while before I bought it and when I changed the oil it was LOADED with carbon and I looked at the oil again today and after about 500 or so miles the oil is starting to take a little color so I thinkthat im starting to work some carbon loose. But ok on a comletly different topic I was talking to a buddy of mine and he just bought a 85 chevy scottlsdale and is taking the tranny and t-case as well as the axels and replacing the axels on his truck and putting his back on the pickup. The pickup is fairly rust free and has a nice bed and I guess is in overall good shape. He says he would sell it to me for 350-400 $ I thought that I could put my 350/th350/mp203 in the pickup but would like everyones opinion on wether or not I should get rid of the blazer 2nd Gen. and buy this pickup???
     
  19. K5dreamer

    K5dreamer 1/2 ton status

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    ok well, first off wed really need to know the engine setup, tranny, gears, and tire setup. if youre running a carbed low compression 383 with a three speed tranny, 4.56 gears, and 44in tires, im afraid theres not alot we can do for ya.

    but in the case that youre driving a mostly stock truck there are a few options to help ya out. first things first, go with a tune up, new plugs, wires, air filter, cap, rotor, fuel filter, yadda yadda. make sure the timing is correctly set.

    one of the best things to do, which boosts power and mileage, is an aftermarket ignition system. preferrably a control box and coil combination, with the capasitive discharge and multispark capasity. a better burn means less fuel is needed for the same ammount of power.

    there are other things you can do, i could outline an entire design philosophy for designing a very fuel efficient small block, but seeing as youre gettin the other cars fixed, i dont know if you wanna completely build a new engine to solve the problem.

    the ignition system upgrade is a quick and easy way to boost power and mileage.

    although i would agree.... swapping in a diesel would be a leap in the right direction ;)
     
  20. W7NB

    W7NB 1/2 ton status

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    Simple Fixes!

    First, try seafoaming the engine and carb to get the carbon and gunk out - I's pour a can through the carb and let it soak like the instructions say and run a can through the gas tank as well to clean up the jets. Will help with the dieseling and ping as well.

    Easy way to improve gas mileage is get rid of the weight. I was running around with hijack, 50 lbs of spare parts, winch recovery gear, big tool box - probably 250 lbs worth of stuff. Took it out and picked up an easy 1 mpg and perhaps more.
     

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