73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: jimbo on August 07, 2009, 09:11:08 pm
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I have been searching through several gas mileage posts and thought it would be an interesting idea to have a thread dedicated to individual trucks mpg and the specifications of said truck, for those of us wanting to improve our mileage, to reference. I know it would interest me to see what different combinations are getting. If you agree, post up.
I suppose I'll start.
1985 C10 Silverado lwb, 4bbl 305, 700r, 2.73 8.5 rear, 235/75/15's 128k miles. Everything is stone stock and untouched from the covered air intake in the grille and the charcoal air filter to the factory exhaust tips. I have averaged 16mpg so far with no regard to trying to save gas. Soon I'll do an all highway trip to calculate the high end of its mileage.
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1985 C20 Scottsdale 454 4 speed factory original dual exhaust, no cats with 8600GVW, 3.21 14 bolt FF rear. LT235 85R16 tires 140K miles, rural use 13 mpg and highway 15-16 driving easy
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87 R15 GMC (re-badged to a Silverado) 350, 700 R4, 3.08 open dif, 235-75R15 Michelin tires, dual exh, mostly rural driving- I get 17-18.6 mpg on 89 octane.
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not sure on mine yet but the farm truck is a 85 C-20 with a crate 305, 700r4, thinking 3.73 gears, and all stock. getting about 9-10 doing farm chores and 13 highway(averaging 55-60mph). that was before the carb was tuned up and i havent found out the new yet.
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87 R15 GMC (re-badged to a Silverado) 350, 700 R4, 3.08 open dif, 235-75R15 Michelin tires, dual exh, mostly rural driving- I get 17-18.6 mpg on 89 octane.
Dang i wish i got 17 MPG! Got a newer motor in there?
Guess mine's a bad example or something but: 1987 Silverado 2WD 5.7L 700R4 - 14.6 MPG mostly city driving. And i agree with the MPG quest, im on the same one. There are a few people here that are interested in it, although a few naysayers. I have been talking to one guy who built a vortec TBI 5.7L with 377 rear wheel hp, (that's like 450 flywheel) and he get's 19 MPG city and around 23 highway. He has it in a 86 blazer or something. It's not bull, he proved it over at Fullsizechevy. He said it's all in the tuning. There is also another guy over there who claims 21 mpg city, but no real performance upgrades. He has some kind of weird intake thing going on where he stacked up some throttle body spacers, and did a couple other mods. Might want to take a look over there. But it's mostly trucks that are newer than ours.
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I have never been able to get more than 8 to 13mpg out of any 73-87 I have ever owned. But my 91 c1500 with a 305, th350 and 3.08 gets consistent 17mpg mixed and my 94 k1500 with 350 4l60e and 3.42 gears gets a consistant 18mpg mixed driving.
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16 sounds about right; You did read my exhaustive/scientific thread on this?
There's going to be even more to the story soon----i have an interesting twist.
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Most of my driving is a 23 mile trip to work and back. Not a lot of stop-and-go. Usually 55 or less..
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I've never calculated my mileage nor could I ever be bothered to. I just enjoy driving and put gas in when I need it. If you are going to try to average what people are getting for mileage you should set some stipulations for calculating it and method of calculation so everyone who participates gives accurate #s
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i have a little notepad in each of my trucks. It has been a habit of mine, each time I put gas in it, i record the mileage odometer, the price paid and gallons put in. Whenever I put gas in it, it is always to fill it up. Anyone want to know what the price of gas was in '96? I have it in notepad ;D
That way I know what my mpg is if I feel like doing a little math. I always know how many miles i got on the previous tank. I can usually go 400 miles on my 91 sub tank, and 200 miles on my 79 p/u 383 stroker tank. They dont sound like good numbers, but, i never run the tanks too low and nearly everwhere I go is within 4 miles of my house (work, shopping, daycare, etc) Lots of urban driving. By recording mileage, I will see if the numbers slip any which indicates I should look at something w/ the truck. Any dip in mileage b/w fill ups is a good indicator for a tune up or something--all else the same (highway vs. city, load vs. no load, angry heavy foot vs. relaxing sunday drive, etc..)
It also allows me to compare one year versus the next or whatever time period if I change something like tires/wheels
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84 C-10 stepside it has a GM Preformance 350, long tube headers dual exaust, th350 and 2.73 gears, 20" wheels and I get 15 mph on rural roads. I haven't made any long highway trips to check that yet.
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79 c10 stock 305, 2 barrel, th350 tranny, i get 15-18 mpg usually, less if i hammer it of course. next week in swapping in a rebuilt 350 and 700r4, so ill update after that when i get numbers in(hoping for a boost lol)
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I am very proud of my setup... 1984 SWB with a 383, 280H cam, 750 Speed Demon Carb, 3.73 gears and a 700R4... Got 12.5 mpg on our last club cruise, and I think I could get to 14 mpg by dropping the secondary jet size and resetting the idle mixture.
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I am very proud of my setup... 1984 SWB with a 383, 280H cam, 750 Speed Demon Carb, 3.73 gears and a 700R4... Got 12.5 mpg on our last club cruise, and I think I could get to 14 mpg by dropping the secondary jet size and resetting the idle mixture.
LOL. If the size of your secondary jetting affects your fuel economy at all, you are driving too aggressively to get any decent mpg.
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I've never calculated my mileage nor could I ever be bothered to. I just enjoy driving and put gas in when I need it. If you are going to try to average what people are getting for mileage you should set some stipulations for calculating it and method of calculation so everyone who participates gives accurate #s
Well I do calculate it, as well as do most of my friends, so it is something that I am interested in. I have toy/drag cars that I don't bother calculating mpg on, but anything that I drive with some frequency or work with, I usually always do.
As for setting stipulations, I guess this thread is a bit more informal than that, and I'm fine with that..
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This is one of the reasons why i got the digital speedo----for accuracy. GPS would probably be even better.
i also fill at the very same station and if possible the very same pump and let it click itself off.
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87 Chev 1/2 ton, V6 FI 3 speed standard, 3.08 gears. I get 23 MPG just jigging around some highway, a lot of country driving around 80 KM/H, and some town driving. Towing a 15 foot travel trailer at 80 KM/H I got 18 MPG.
Had a 87 F-150 with a NP435 4WD 3.08's and a 300 and could never get better than 13 MPG. IH Scout 800 with a 304/automatic and 3.73's does about the same as the ford on the highway.
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Wow that little v6 is really doing its job. I had two '97-up f150 v6's that wouldn't pull down that good of mileage, kudos.
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1991 R3500 Crew Cab, 350 TBI/4L80E, stock gearing (4.10), stock tire size. 13/17mpg
1987 R10 Regular Cab, 305 TBI/700R4, stock gearing (2.76), stock tire size. 18/22mpg
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So I have been doing a lot of short distance driving and apparently the '85 does not like that. Without some higher speed cruising thrown in, the mileage goes way down. It must be the 2.73's.
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Dang, something must be wrong with my truck lol. ;D I wish I got 18 mpg, instead of 14. Four more MPG's would help me out a lot in the wallet. And im not a leadfoot or anything like that. I drive like a granny, cause I can't afford to fix right now it if it breaks.
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I stuck some new plugs in to replace the old rusty ac's and replaced a lot of 25yr old vacuum lines along with an oil change, air filter, and a pair of new front tires. I think I have bumped my mileage to 17-18mpg hwy. The vacuum leaks helped a ton, but I have one left. The vacuum advance is leaking so I have unhooked it for now, so hopefully with a new one, it will do much better.