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View Full Version : Improve your gas mileage?


Robertboxerboy
05-18-2009, 12:54 AM
Ok so i am 15 right now and i get my liscence here on december 10th, even tho that is quite awhile away im sure you can still imagine hust how estatic i am :frantics: . But i have a few questions. Mt dad has an old GMC 4x4 that was his first truck (its like 20 something years old) and i have always wanted it. But we both agreed a jeep would be nice for me too. But if i could get that truck it would be like my baby. But the problem is, its a gas hog. The trucks payed off so i wouldnt be making car payments, just buying gas and paying insurance. So i was wondering (besides everything else i know i will have to upgrade) is there anything i can buy that would improve the gas mileage on it?anything you guys might know would be amazing help!

Mac
05-18-2009, 01:08 AM
Ok so i am 15 right now and i get my liscence here on december 10th, even tho that is quite awhile away im sure you can still imagine hust how estatic i am :frantics: . But i have a few questions. Mt dad has an old GMC 4x4 that was his first truck (its like 20 something years old) and i have always wanted it. But we both agreed a jeep would be nice for me too. But if i could get that truck it would be like my baby. But the problem is, its a gas hog. The trucks payed off so i wouldnt be making car payments, just buying gas and paying insurance. So i was wondering (besides everything else i know i will have to upgrade) is there anything i can buy that would improve the gas mileage on it?anything you guys might know would be amazing help!

Post me a couple pictures of it , or just lemme know the year.

Robertboxerboy
05-18-2009, 01:12 AM
he said its an 1980 GMC 4x4 so its almost 30 years old lol

Blmfighter
05-18-2009, 01:25 AM
What motor does it have in it? and what kind of trans?

Mac
05-18-2009, 01:27 AM
he said its an 1980 GMC 4x4 so its almost 30 years old lol

1/2 ton or 3/4 ?

Mac
05-18-2009, 01:28 AM
What motor does it have in it? and what kind of trans?

If i had to guess id say 350,th350 np203

Robertboxerboy
05-18-2009, 01:28 AM
mac seems to be the genious here lol

Robertboxerboy
05-18-2009, 01:40 AM
said its a 1/2 ton short bed

Mac
05-18-2009, 01:41 AM
If its a half ton , being a 1980 it could have any number of gear sets in it , could be 3:08's . 3:42's . 3:73's or 4.11, Not many halfers had 4:11's unless they were special ordered so count on something a little higher. if its a 3/4 ton its more than likley a 4:11 gear set. Being a 1980 model no mater if its a half ton or 3/4 ton , the front axle is a corporate 10 bolt. They quit installing dana 44 front axles in 1977 . Unless someone swapped the axles and put in a 44 up front then its the corp 10 . the rear if its 3/4 ton is a 14 bolt corp , the half ton model will have a standard 12 bolt. 1980 was still a carbed motor , tbi was still a few years in the making . lets say it is a 350 small block chevy. Its a carb model , probably still has the stock qaudrajet carb on it , Nothing really to improve gas mileage with , About the only thing you can do to it is throw on a little taller tire , Give her some longer legs and it should improve a little bit , dont get super silly with some big meats , something that will make the motor work harder inturn burn more fuel . Just a size or 2 taller.

Now if it does have a 203 tcase in it , then that is a full time transfercase which was a dumb idea from the factory , your spinning the front shaft constantly because the 203 has to to spin the rear output . Unless someone has put a part time kit in it which is highly unlikely .

Take a picture of the transfercase for me , preferably where the shifter attatches and ill tell you what it is . a 203 has 2 shifter arms hooked to linkage on the t case , a 205 has 2 shifter rails coming out of the transfer case , or just give me the shift pattern off the knob and ill tell you what it is . a 205 is all the way forward is 4 low , then neutral , then 2 hi then 4 hi . A 203 if i remember right is all the way forward is low loc , then low , then neutral then hi then hi loc. If the tcase is aluminum then it has been swapped in and its an np208.

Like i said , take me some pictures of the truck , under the hood , take me a picture from underneath of the tranny pan , the transfer case etc , I never even thought it could be a manual with an sm465 . shoot me some pics and ill tell ya what all it is . Get a pic of the sticker if its still there on the inside of the glove box lid with all the options on it .

Mac
05-18-2009, 01:43 AM
Ok , i posted all of that up above without reading your other post.

half ton short bed with a manual , im guessing its a small block 350 . the transmission is a saginaw sm465 3spd with granny low making it a 4spd . theres a good chance its got a 205 behind it , and possibly 3:42's , or 3:73's 3:42s are a GREAT daily driver gear if it has them

Mac
05-18-2009, 01:44 AM
whats the front axle got for hubs ? Lock outs or just a hub cover plate . If its got lockouts you dont have a 203 which is a good thing.

Robertboxerboy
05-18-2009, 01:52 AM
lock outs

Mac
05-18-2009, 01:54 AM
lock outs


good . Its got a 205 in it then . well i say it SHOULD have a 205 in it . It might have a 203 with a partime kit in it . Or a 203 without a partime and it just runs in 4 hi with the front end unlocked or 2 hi with the front end locked.

Pictures would help but those are the options lol

I know it sounds like a bunch of different crap , but ive been through em all up down and sideways and seen it all done to em lol.

rearnakedchoke
05-18-2009, 01:58 AM
get a honda ridgeline

Robertboxerboy
05-18-2009, 02:04 AM
205 with a 4 speed manual

Mac
05-18-2009, 02:05 AM
If the sticker isnt on the glove box anymore and you want to know what gears it has without pulling the differential cover and counting teeth , here is a little trick that will tell you .


Jack the back ind of the truck up , just enough to get the tires off the ground . Put the transmission in neutral . put some blocks in front of the front tires so it doesnt roll and put a jack stand underneath it to be safe.

Now lay down and take notice where the rear drive shaft yoke is pointing where it connects to the rear axle at the u joint , mark one of the u joint caps so you dont lose track of which one you are watching . Now slowly spin one of the tires so the marked cap is pointing straight up .

Now your ready , have a friend slowly turn one of the tires . the drive shaft should start to spin . have your friend make one full revolution with the tire . actually , you should put a chalk mark on the tire pointing straight up , so when he spins it he can stop it at the same exact point .

now while he slowly spins the tire one revolution you count how many revolutions the ujoint cap that you marked makes to one tire revolution . If it goes 3 and just a hair farther it is a 3:08 gear ratio . If it goes almost 3 and a half revolutions it is a 3:42 gear set , 3 and 3/4'2 of a revolution it is a 3:73 gear set , if it makes it just past 4 revolutions it is a 4:10 or 4:11 gear set.

Robertboxerboy
05-18-2009, 02:09 AM
ddaammnn im just gonna take a wild guess and say you have been around cars and trucks your whole life?

Robertboxerboy
05-18-2009, 02:16 AM
but he's an old man and went to bed lol so ill ask him if he knows the ratio when i get home from school tomorrow and ill post it

Mac
05-18-2009, 02:32 AM
Well , like i said , to improve gas mileage , throw a little taller tire on it and have fun . thats about your only option , unless you want to throw an automatic in it , and start changing gear sets . But i wouldnt touch it , i would have fun with it the way it is , besides Jeeps are for girls . Ive got a video from last weekend to prove it ha ha ha . And there are so many different options you can do to an old chevy 4wd .

Heres a few of mine ive put together . THe black 86 is one my brother just finished and sold and the ole grey burb is my dads

Ive had my hands in a few of em lol.


http://i47.photobucket.com/albums/f186/uhmname/greendriversidewithstar.jpg

http://i47.photobucket.com/albums/f186/uhmname/green68burnout.jpg

http://i47.photobucket.com/albums/f186/uhmname/orange.jpg

http://i47.photobucket.com/albums/f186/uhmname/orangestepwhiteletter.jpg

http://i47.photobucket.com/albums/f186/uhmname/blaze344.jpg

http://i47.photobucket.com/albums/f186/uhmname/pair82.jpg

http://i47.photobucket.com/albums/f186/uhmname/imag0013.jpg

http://i47.photobucket.com/albums/f186/uhmname/PICT0804-1.jpg

http://i47.photobucket.com/albums/f186/uhmname/PICT0829.jpg

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http://i47.photobucket.com/albums/f186/uhmname/PICT0751.jpg

http://i47.photobucket.com/albums/f186/uhmname/binderparade.jpg

http://i47.photobucket.com/albums/f186/uhmname/jimmyfront.jpg

http://i47.photobucket.com/albums/f186/uhmname/blower3.jpg

http://i47.photobucket.com/albums/f186/uhmname/574doorandred57.jpg

http://i47.photobucket.com/albums/f186/uhmname/55fullside.jpg

http://i47.photobucket.com/albums/f186/uhmname/Imag0005.jpg