70-80s Gm Pickup Mpgs?

[strafingmoose]

Hey guys!

 

Is there any old timer here that drove older pickups from the 70s or 80s, with comparable V8 engines of today (4.8, 5.3, 6, etc.) ?

 

I'm just curious as to know if the technology improved that much.

[KidHauler]

I got 9 in my '75 Jimmy. Maybe 10 downhill with a tail wind. The '89 C1500 305ci gets 16ish with aggresive tires.

[doverarjim]

I can not give the exact numbers I have thrown out my mileage book for my 1976 Chev Scottsdale C 15 pickup. It was a special order (which you could do back then) with heavy duty rear end like in 3/4 ton truck but with out the full floating axles. A couple ordered the truck and slide in camper and the husband got killed at work the week the truck came in to the dealership, they had financed it with gmac and had the accidental death insurance on it so the wife got the truck paid off before she picked it up. She never did get the camper for it and they kept it for 4 years and never put a back bumper on it, and traded it in for a Jeep(????) I bought it for $2800 with 22,000 miles on it. As best as I can remember it got about 10 in town and 12 to 14 highway. It was a 350 with a turbo 350 trans and 3.73 gears. It was a good truck until a little over 100,000 miles and then I had to rebuild the trans and when it was out of the truck someone stole the carb and dist. out of it sitting beside my house!!! Replaced those parts and kept it intil I bought a 86 GMC 2500.

[RaysZ71]

My dad had a 86 blazer, 305 4spd manual with 342 gears. It got like 19 on the hwy once.

 

The gas mileage has not improved much since the 80s, but the engines now make about twice as much power and hare heaver than they were then.

 

That 305 blazer only had about 160 hp. A 300+ hp 5.3 will get the same mpg.

[s-ten]

The addition of overdrive transmissions made the biggest difference in mileage then anything else done to the engine I think.

[HawkScot]

73 3/4 Chevy, 454 2WD auto. 8-9 towing, 12-14 highway not towing. Lots less when playing. Very hard not to run hard with a 454, just sounds nice every time you push the accelerator down.

[Wingnut]

The BEST I ever got out of my '81 4x4 was 12mpg. It averaged around 8-10. That was with a 400 small block, it got worse when I put a 327 in it. The BEST I got out of my '02 4x4 was 22.

 

I'd say that newer ones are MUCH better gas-wise. They'll also tow more, last longer before needing a rebuild, and are 100x more comfortable...In my opinion of course.

[strafingmoose]

I'd say that newer ones are MUCH better gas-wise. They'll also tow more, last longer before needing a rebuild, and are 100x more comfortable...In my opinion of course.

 

You tell me. My dad had a Dodge back in the early 80s and the cab didn't even have a finish inside it, you could see the metal from the inside. It was green, but after 2-3 years, they started calling it the leopard frog because of the rust spots.

 

Nothing to do with even my basic SL 2003 model with such comfy seats

[BAD2500HD]

75'Chevy K15 with a 350 and auto not sure of gears to long ago ! it was my first truck i got it when i was around 19-20 yrs old, got around 10 to 12 at best thats with 235/75R15 tires. some diffrents , my 07' Chevy 1500 was getting 16.8 to 17.1 this fall it has now dropped to 15.5 not to bad i guess since i have had to use the 4wheel drive alot sofar .

[I-H8-4Ds]

'72 Chev with low compression 350, 4 bbl carb, 4.10 axle- 10 mpg tops no matter what. After about 1970, compression went down and along with it came the prehistoric emission controls. Need I say more....

[intmd8ak]

They claim 14/18 MPG on my 07 Silverado 4.8L, but I've only been averaging a little over 13 MPG real world. I could see getting 18 MPG on the highway as I did get 18-20 MPG highway in my 01. Either way I have an 81 C10 w/ a 350 that's probably making between 250-300 HP at the crank, has 3.08 rear end gears and averages about 11-12 MPG, and all highway could get into high 13 MPG range. If it had an overdive, like newer trucks, it could probably be getting 15 MPG. Truck to truck comparison, mileage has improved slightly.

 

However, if you were to put one of the newer engines in an older truck, you would probably see huge improvements in mileage due to not having all the mandated BS that the new trucks are required to have. My 81 tipped the scale at about 4000lbs, while my 07 runs about 5300lbs.

[Cheekster96]

I have a 87 V20 truck with the 350TBI, 4x4, 4.10s and a Turbo 400 tranny. tires are 235/85/16s. i put on an edelbrock performer intake, holley throttle body, 1.5 crane roller rockers, hedman mid length headers and a dynomax exhaust. truck gets 12 mpg. rides like a truck. leaf springs and a live axle up front.

 

Lee

[wayneo]

Years ago i had a 3/4 ton GMC with 350 automatic and it was anywheres from 7 to 10 mpg

[Workin8.5]

I still drive my 1969 3/4 Longhorn (8 1/2 foot wooden bed) Custom Camper.Very heavy truck in it's day because of the 1 ton frame. 350 motor with "close ratio" truck 4 pd stick. I drove it 700 miles all freeway and got 15.5 MPG. It averages 12.

A buddy got a brand new Tundra and I heard him griping about getting 14 MPG. I've heard that the new 3/4 Chevys get 12-13. But they have WAY more power.

[dreisenauer]

I have a '79 (getting redone) 2WD with 350 4spd manual 3.08 gears stock carb with a few extras that gets 15-17 and 10 pulling. This pickup was stronger than any other pickup i had until my 04 GMC. It still has better torque for pulling though.

 

Had a '85 4x4 305 that got 13...and that's it. But now it's got a new 350 and my dad drives it.

 

Have an '87 Suburban that used to get 16-18 highway but now it only gets around 15 but it has 200K miles.