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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: grayharville on June 14, 2008, 09:16:03 pm
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hey yall I'm wondering what mileage you get out of your 73-87, reason being, I had to find something with better milage than the 3/4 ton, (it gets 10!!) so to keep my dad happy,and me ;D I got my stepside. I plan on running a 350 TH350 combo, or a 350 700r4 if i can find a tranny, what kind of mileage should I expect? I have a 25 mile round trip to school everyday, my dad is trying to make me drive a POS ford focus, but i refuse!! I also have a 305 in unsure condition(never cranked it) but it had a small engine fire so idk. IM JUST AFRAID OF THE PERFORMANCE OF THE 305 OVER THE TRIED AND TRUE 350! I really just need some opinions, and some gas mileage numbers ;D so i can see what other people are getting! thanks
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My extended cab gets about 18-19 on the highway, and about 13-14 in town if driven normally.(worse if I drive like a maniac) It has the stock 305 w/ 700r4 and i think 2:73 gears. It won't win any races, but is fun to drive. It all depends on your driving habits. My wife has gotten 15mpg with her 3/4 to. It has a 468 /400 tranny and 4:11 gears. I best about 12 with the same truck. It really depends mostly on you. More horsepower doesn't necassarily mean worse fuel mileage. Think of it this way. If it take 60 horsepower (JUST AN EXAMPLE) for your truck to run 70 miles per hour down the freeway. A stock engine may need 1/2 throttle to maintain this requirement, where as a performance engine does the same at 1/4 throttle. Key reason is efficiency of the motor. Now, if you stomp on it alot, and like to hear the pipes rattle more than usual, then your mileage will go down either way. Like I said, it depends on the driver. I don't hotrod my extended cab, because it doesn't have that kind of power, and I am happy just driving normally, but her truck has over 500 hp and I can't control myself and keep from laying my signature ( burnt rubber) everytime a mustang or Camaro pulls up a gives me a funny look. ;D My wife could care less, thats why she gets the Firebird T/A, I would be in jail in a matter of hours.
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350/th350 2wd, gears aren't entirely known (likely 3.08, it runs at 2300-2400 rpm at 65 mph, whereas my GMC with 2.73's ran about 1900-2100 at the same speed) and I see 8 mpg in town/13 mpg highway at 60-65 mph...my trans swap (nother th350) will probably pull my city mpg up to about 10-11, as it'll do away with the bad modulator valve and slipping first gear.
My '84 GMC 305/th350/2.73 saw 10-12 MPG city, 15-17 highway with dual 2 1/2" original 40 flowmasters.. as long as you kept your foot out of the secondaries and didn't romp on it and make the 305 wheeze in town..
Generally, more horsepower has a direct relationship to the amount of lead in your right foot..the more horsepower you have, the more that right foot weighs..
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My 91 Crew Cab gets 13mpg in the city, 17mpg on the highway. It is a 1 ton with a 350TBI and 4L80E.
My 87 Reg Cab gets 17mpg in the city, 22.5 on the highway. It is a 1/2T with 305TBI/700R4.
Unless you already own the Focus, it isn't going to do you any good. With payments and higher insurance in addition to regular maintenence/wear parts, you would have to drive it for about 7 years to recoup you cost. With the truck you already own it so you only have regular maintenence/wear parts as an expense. I would add all of it up and figure if it was worth it to get a new car.
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I think im gonna sell my th350 and the th400 and pick up a used 700r4, and yes, we do already own the focus, my sister tried to trade it in and with my pioneer radio taken out, the offer was 100$, yep 2 zeros!! but i will NOT drive it, I would rather pay for the extra gas in my stepside than drive it lol call me stubborn but I love my truck! And at 6' 1" that little gocart(focus) is hard to get into!! ;D
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Please refer to my post entitled, "MPG Pt.1:"
http://forum.73-87chevytrucks.com/smforum/index.php?topic=8474.0
i can't comment on the fuel mileage of my second tank yet because i don't drive it that often.
Anyways, the way to get good mileage is small cubic inches and small frontal area. I.e., chevette, camaro, monza, most hondas, and, wonder of wonders-----ford focus. i would strongly recommend driving it.
The way to get better mileage with a 73-87, or for that matter, any truck is to move down on cubic inches. I.e., 262 v-6, 250 I-6. Or if possible, diesel. The factory has proven that a truck with 250 cubic inches is sufficient. Unless your're emotionally attached to the one you have now, it would be the most economical way to trade for a truck that already has the 4.3 installed.
It would be interesting to know what owners are getting mpg-wise with the following engines:
a) 4.3 v-6 with EFI
b) 5.0/305 with TBI
c) 5.7/350 with TBI
d) We already know that anyone with the 6.2diesel is getting at least 24, so we won't worry about them for now.
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My 87 2wd shortbed with the TBI 305, 700r4, dual 2 1/4'' exhaust, K&N filter, 265/75/15 tires, and what I believe to be 3.08 gears, gets about 12-13 city and 14-15 highway. I believe when I get rid of those big tires, and drop down to a smaller size, my mileage will go up since I feel the tires rob some power, and even causes the transmission to "hunt" in and out of overdrive on the highway on the uphills.
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77 350/350 ,,11-12 mpg :'(
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85 custom deuxe
the old 4.3 my truck had got about 7 city 14 hwy.
dont know why but it did.
the 355 gets about 11 city 18 hwy.
2.73 gears and a th400
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85 custom deuxe
the old 4.3 my truck had got about 7 city 14 hwy.
dont know why but it did.
the 355 gets about 11 city 18 hwy.
2.73 gears and a th400
i can answer that...it had an underpowered motor in a heavy truck with horrid 2.73 gears...lol
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what rear diff. ratio should i have for a 350/700r4 combo? I plan on lowering the truck, and running smaller tires, my dad thinks in order to get better mileage I have to run taller tires, but these are 2 reasons I dont think so,
1. 33 inch tall tires would look horrid on a lowered truck ;D\
2. The tires on the focus are tiny, yet it gets 35 mpg, WTH!?!
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How small are we talking in terms of tires? 3.42s would be very viable..I wouldn't go shorter than an equivalent of 225/75/r15's with that ratio though..taller tires = POTENTIAL theoretical better highway mileage, but worse city mileage...same with higher gears, 2.73's would probably be fine mated to a 700r4 with 235/75/r15 if you run 75-80 mph a lot..but it would DOG at lower speeds, especially in OD..my dad's '83 f150 has a 4 spd manual OD trans with 2.xx gears on 31x10.50's, and you cant put it in 4th below 55 mph, or the truck runs at 500 rpm..as a result, it gets 9-10 mpg city/24 highway @ 60-70 mph (300 inline 6), and eats clutches like a kid eats candy.
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my cousin has 275/60 kelly chargers on 15x10s on his 84 swb and I like the way it looks, so probably around that size, I have a 10 bolt that came out of an 83 with700r4/ 305 and a 12 bolt that was in an inline 6 with 3 speed on the column, I have no idea of gearing in either, any ideas other than me having to put the truck on stands and roll the tires to figure it out?
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pop the cover, the fluid probably needs to be changed anyway..check and see if the ratio is stamped on (i think) the ring gear..
275/60/r15s are 28 inches tall, 235/75/r15's are 28.9 inches tall, 225/75/r15's are 28.3 inches tall..3.42 gears with a 700r4 would be a good multi-use gear set..
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kool, thanks ;D
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1) Tire diameter generally doesn't mean much for mpg if the gears are right; If the vehicle has higher gears, i.e., 2.73 etc., then the car doesn't need really tall tires and, in fact, taller tires may hurt mpg because now the ideal torque curve may be messed up. (rpm too low on the highway)
2) i drove a focus on mon. night, and while i am in no way a ford fan, i strongly urge you to drive that in the meantime while you figure out your mpg thing with the truck.
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79 C-10 LWB. 5.3L 4L60E trans, combo city highway, pulled down 19.5 mpg first tank. And Im flogging on it from time to time. If I can keep my foot out of it, 21 isn't out of the question. 255-70-15's and 3;08 gear.
I agree with Stewie, it may be a POS ford, but dude, its going to get 30 if you drive it like you stole it, and better than that if you baby it. Tint the windows solid black and park far away from anyone that might see you, and deal with it. You will save money for your truck.
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I have something to drive, our 81 jeep cj5 on 33x12.50 bfgoodrich it has a 151 iron duke thats worn out, and Ive convinced my dad to let me put my 305 in it!! I need to address the steering, as the box is worn (lots of play) I may uprade to power steering when I put the 305 in, but for now Ill drive it with the 151 until its on its last legs then I can swap motors, and drive the jeep when the weather lets me, besides, JEEP=Chick magnet!! oh, and 25 mpg ;D
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my truck gets about 4 mpg if i baby it lol
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Read my sig.
Does not seem to matter if I pull a boat or drive 50 or drive 70. I get 11. Got close to 12 on my last camping trip, but still in the 11's.
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I hope mine gets 15-20 somewhere in there and I think it may be possible, but idk my dad once had a 83 longbed with 305/th350c and got 18, I know I have a 350, but will have the benifit of overdrive and somewhat lighter with my shortbed, It will hardly ever get driven on the highway, as I live in the country and the road to school is a twisty 2 lane, speed limit around 50-55, that will be most of my driving, and the occasional trip to town and leaving a couple signatures ;D
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According to this, 20+ is possible:
http://www.73-87.com/7387info/ads_GM/82_20mpg.jpg
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1) again, that special edition engine is the LE9 305.
20 mpg in a 73-87 truck is possible with a 8 cyl gas engine and i'm going to prove it.
2) to confuse the issue further, apparently edlebrock has come up with an engine that produces 675 hp and gets 19.8 mpg installed in a 67 chevelle:
http://www.edelbrock.com/automotive_new/misc/spotlight/sl.shtml
i have my doubts because the "test" took place on a dyno, not outside on real roads---this doesn't take into account wind resistance. Admittedly 675hp can probably overcome any aerodynamic resistance at 70mph, but still.
i think the engine is "only" 13k or something?
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20mpg City, or highway? Mine is getting 22mpg highway @65mph with the 305, so it isn't that far of a stretch. I could get better if I slowed down to 55mpg most likely.
Keep in mine times have changed, people don't think twice about running 80 on the highway now and the limit is 70. Back then it was 55....
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We have hundreds of miles of highway where the legal limit is 75 or 80 miles per hour, and people are still goimg 10+ miles over the limit, then complain about fuel mileage.
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ok, now im on the lookout for a 700r4 with all the linkages, etc. I havent done anything the stepside, been cutting hay/ repairing tractors, and have no time!! I want to pull the 350 and put in new gaskets, like a comp xe268 or xe270 cam, something to give it a lopey idle whele remaining reliable, and an aftermarket intake, likely edelbrock, with a holley carb believe its a 650, then spray it chevy orange and drop it back in, is my cam a choice good for a daily? thanks
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mine gets way north of 20, but I also have a diesel...I love the fact that everyone I know is like you pay how much for gas, but what they don't understand is that dollar per mile is better than with my tahoe...
Chuck.