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305 vs 350 gas mileage. much difference?

Discussion in 'The Garage' started by OffRoad, Aug 6, 2005.

  1. OffRoad

    OffRoad 1/2 ton status

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    hey, been thinking about a pickup lately. i'd rather have the 350 but don't want 10 mpg. i've driven trucks with 305 and they were ok, but nothing too great.

    i'm not even sure if a i want 4wd. i mean it'd be great but i'll start fooling with it. 2wd will keep me out of trouble.

    a c10 or 20 with 350 700r4 and some 31s would be great. but i'll take 29s.

    the sammi is getting kinda small for a daily driver.
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Didn't notice much difference when I went from 305 to 350. Variables exist, tranny, rear ratio, etc., but I imagined WORSE mileage when I went to the 350 truck, but it was actually just a bit better.

    I'm changing my stance. If the 2WD truck is lighter, it's going to get better mileage. The more weight you can shave, the better.

    Overdrive is always good,, but some decent rear gears would really help "felt power" as well.

    I suspect a 2wd, 350, 465, 3.08 geared truck would get pretty good mileage. Not sure how good acceleration would be, but the mileage should be about as good as you can get in one of these things.

    Best I've heard out of any of these trucks, gas, has been about 20 hwy. If you are anywhere in the 15-20MPG range, you are doing good IMO. Even my dads 6000lb 454 equipped truck gets 11MPG on the freeway. Drop 1000lbs and 100 cubic inches, you can see that over 10MPG is very reasonable for a 350 in these trucks.
     
  3. OffRoad

    OffRoad 1/2 ton status

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    yeah if i can get 20 mpg i'd be happy. tempted to go newer so i can get a 5 speed (for o/d), but it's harder to find a cheap (newer) truck.

    my dad has a 90 c10 with 4.3 v6, 465, and 3.08s. he got 28 mpg on the highway. but that's canadain gallons so it might be worse in us galons, i'm not sure, i don't know how all that stuff works.
     
  4. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    20mpg is cake with a fuel injected 305 in something light such as a 2wd shortbox. It's mostly about gearing though. 3.42s with 31s and a 700R4 or 3.08s with 31s and a SM465.

    I was getting 16-17 around town with my wheeling rig. 40s, 3.73 gears, SM465, a cab, a frame, and a core support being powered by a tired TBI305. Pretty much never had to exceed 2,000rpm. I don't know what's going to happen when it gains around 800lbs of junk.
     
  5. OffRoad

    OffRoad 1/2 ton status

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    you don't find 40s a little tall for 3.73s?

    i don't really care whether i get a shortbox or longbox. the most i'll have in there is an atv or a couch for parties. :D

    i just want a bit of power (350). i've driven gutless stuff up till now.

    again this is all just rolling around in my head, i'm not looking in super savers or anything. the sammi is getting kinda small. but if a get a truck i also loose the back seat. :doah: :( i like having the backseat for chicks. so then there's the idea to get a 2wd sub. they're not to hard to find. lots of old guys have em. i could always throw a locker in the 2wd and it'd do pretty good.

    maybe i should get a car. like a 4 dr chevelle or something...

    if this country would get personal insurance instead of by-the-vehicle insurance i could have all the vehicles i wanted. i'll call and check what insurance would cost for 2 vehicles.

    youth. because it's more fun than being old.
     
  6. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    3.73s are way too tall for 40s. But it's not bad driving around when there is no weight. In low/low range it crawls at 1.3mph. I drive it around in 3rd gear most of the time. It doesn't like to hold 4th unless i'm going faster than 55mph.

    I have a difficult time investing $400 in half ton axles to regear them. I already have $450 into steering and $300 into the brakes. By now, I could've bought a D60 but I could buy the parts over several months with the half ton junk.
     
  7. neverendingproject

    neverendingproject 1/2 ton status

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    A 305 and 350 are have very different charachteristics in the same vehicle. In a light vehicle you wont notice too much of a difference except that the 305 will have better mileage and the 350 will have better power. In a heavier truck (anything bigger than a 2wd single cab) the bigger motor will make more power and better mileage. A 305 has to work too hard to move a heavier vehicle, and therefore your foot will need to be closer to the floor with a 305 than with a 350. I had a 350 tbi in a 3/4 ton long bed 4x4 and i got 15-17 where-ever I went. I had a 305 in a f/s blazer and i got 8-10 because my foot was half way to the floor to get it moving. both vehicles had same sized tires and close gearing.
     
  8. big_truxx

    big_truxx 1/2 ton status

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    gm designed the 305 with fuel economy in mind.... but... i would think the difference would be very little. and as far as reliability and longevity and everything else consiered i would not want to go with a 305 over a 350. :waytogo: also the 350 has more power and for it to drive the same weight ion the same setup will be workikng less hard than the 305. so i think the 350 is the best choice by far.
     
  9. muddybuddy

    muddybuddy 3/4 ton status

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    man, im struggling to get 9-10mpg with 35s 700r4 and 373s. hopefully when my 3/4ton 410s are in ill notice a big difference. haha
     

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