Average Gas Milage-V8 & V6 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Matt67 · 11-04-2003, 10:15 PM

I was wondering what kind of gas milage you guys get with your 350/350 trucks. Please include whether it has a/c, pwr steering, lwb or swb. I want to get good milage, but hate straight 6's. I'm thinking of getting a '72 body and putting in a newer carburated V6 engine with a TH/350. Does the V6 get much better milage than a V8?

Also, what different will a fuel-injection conversion, or a 700-R4, or both make? I'm sure out of all the people on this board someone will have one of these combo's.

Thanks in advance, Matt

lukecp · 11-04-2003, 10:24 PM

I have a mildily built 325hp 350 with a TH350 in a LWB pickup....PS, PB, and 3.07 gears. The truck weighs 3980 pounds without me in it....i get about 13 mpg on average on premium fuel.....most stock 350's tend to get 10-12 mpg...if you drive easy and the engine is in good tune, 15mpg is possible on the highway.

If you want to go for gas mileage.....don't buy one of these trucks. The V6 will have to work harder to pull the truck around town, so gas mileage will be only marginally better, or even the same. Plus it won't have the power and cool sound of a V8

EFI will help out quite a bit....especially if it is multipoint EFI of some kind. However...it is expensive and fairly difficult to retrofit. A 700R4 will usually pick up about 2mpg or so on the highway (from everything i have read anyway....), and would be an excellent idea if you plan to drive the truck on the highway alot.

I would build a nice mild 355, add a 700R4 or 200R4 tranny, and use 3.73 gears....the truck would get an easy 15mpg on the highway if it tuned good, and have plenty of acceleration around town with 3.73 gears

**BIG ORANGE** · 11-04-2003, 11:33 PM

72 swb 402/400 turbo 308 gear pb,ps,duals,600cfm holley,electronic dissy. 15mpg!!!!!!!!! OYEAHHHHHHHHH

shuttermutt · 11-04-2003, 11:42 PM

I haven't run the numbers officially, but I think I'm getting about -23 MPG out of my 68. Yep, that's right... I'm pretty sure I pay about $40.00 per mile (regardless if the truck actually moves or not!

*Phillip Johnson* · 11-05-2003, 12:48 AM

The mileage in these truck suck. once you understand that 15mpg is totally *****en and the avg is really 10 mpg, then you will be correct with the numbers that anyone claims to be getting. The best I EVER got was 15 mpg and that was in a 71 350/350 turbo with 308's on a good day. I did get 13mpg in my 72 3/4 4x4 between Chico and Las Vegas. How? I couldnt tell you. I think I had the wind behind me. The facts are, these trucks get 10 mpg. City ,Freeway, or 55mph or 70 mph.. Ive had so many of these I cant remember them all.

*Phillip Johnson* · 11-05-2003, 12:48 AM

The mileage in these truck suck. once you understand that 15mpg is totally *****en and the avg is really 10 mpg, then you will be correct with the numbers that anyone claims to be getting. The best I EVER got was 15 mpg and that was in a 71 350/350 turbo with 308's on a good day. I did get 13mpg in my 72 3/4 4x4 between Chico and Las Vegas. How? I couldnt tell you. I think I had the wind behind me. The facts are, these trucks get 10 mpg. City ,Freeway, or 55mph or 70 mph.. Ive had so many of these I cant remember them all.

*Phillip Johnson* · 11-05-2003, 12:48 AM

The mileage in these truck suck. once you understand that 15mpg is totally *****en and the avg is really 10 mpg, then you will be correct with the numbers that anyone claims to be getting. The best I EVER got was 15 mpg and that was in a 71 350/350 turbo with 308's on a good day. I did get 13mpg in my 72 3/4 4x4 between Chico and Las Vegas. How? I couldnt tell you. I think I had the wind behind me. The facts are, these trucks get 10 mpg. City ,Freeway, or 55mph or 70 mph.. Ive had so many of these I cant remember them all.

**StingRay** · 11-05-2003, 12:54 AM

I can get 14 mpg with a mild 350, 373 diff, th350 and cruising 70. I've also managed that at 60 with a 2500 pound flat deck (empty).

68 Suburban · 11-08-2003, 01:02 AM

17 mpg on flat land. 350/turbo 400/3.08/HEI.

74Pumpkin · 11-08-2003, 01:36 AM

Around 9 mpg. No ac. Short Stepside. 3.08 rear. Mild Mod on the engine. With only one of the 15 gal tanks working. I stop alot to fuel up....

With the gas prices hovering around $1.60 Well I drive the PT cruiser to work. ( I Know I Know! No egg throwing please!)

palallin · 11-08-2003, 02:13 AM

My '67 SWB Fleet w/ 327/Q-jet, 4-spd Saginaw, 3:07 12-bolt was capable of 18+ on the highway, 15+ in town. Those are hard numbers, checked multiple times. Best highway mileage was a fraction over 20.

Cat Fuzz · 11-08-2003, 03:09 AM

I have a 68 3/4 ton 2WD with some short rear end gears. Don't know exactly what ratio. I get about 12 mpg. The motor is a 327 that I used to have in a 77 Monte Carlo. That car had 2.56 rear end gears and I got 22 mpg.

*Phillip Johnson* · 11-08-2003, 03:19 AM

20 mpg with a 327..That is great

71-longbed · 11-08-2003, 04:27 AM

i got almost 16mpg with my 350 on a 90 mile trip ..... i have 3.08's... and no AC
i seriously dont care what i get around town

still better than some new dodges i bet

EGLIDERIDER · 11-08-2003, 07:30 AM

I have a '93 Dodge Dakota V6 w/ a 5-spd that I bought new and it's never gotten better than 22MPG on the road and about 18 in town. However, my '87 Corvette got 20+ in town and MUCH more power and that pleasing rumble.

Mike

**Stocker** · 11-08-2003, 11:48 AM

PITA to check with triple tanks, and lousy with mostly short trips. Years ago I got 11.5 mpg on a cross-country trip, K20/350/350 with 4:10s. IMO, if you want mileage in a full size truck, buy a diesel.

Hugger · 11-10-2003, 12:03 PM

I just checked the other day, not as bad as I thought it was going to be.
12.5 mpg with stock, not much done but maintenece, daily driver. 350 / TH350

Green72GMC · 11-10-2003, 01:31 PM

I got a 305 v8 with 3.40 gears. I get 17-18 highway, I dont know what I get city. I have no a/c or power steering. swb, 1/2 ton.

bpmcgee · 11-10-2003, 02:25 PM

Last long trip I took I got over 13 MPG on the highway. My setup:

71 Blazer, 350. Running on 7 cylinders, it turned out (round #7 intake lobe). Unkown compression. Mild cam. 882 heads. Dynomax headers and dual 3" exhaust.

3.08 gears. SM465 tranny.

Holley ProJection 2d TBI.

The new engine I just dropped in has Vortec heads and a roller cam. I hope to do between 3-5 MPG better on the highway with that setup.

Brian

**Yukon Jack** · 11-10-2003, 02:41 PM

9 to 10 mpg - 69 K20, when the truck was stock with the mighty 307, and 4.56 gears.

ts71281 · 11-10-2003, 03:44 PM

My 70 SWB 468 BBC truck gets 13-15 MPG on the open road. That's with 3.73's and a 3spd on the column. My engine combo is a 9:1 compression motor with pocket ported heads with the 2.06/1.72 valves, 236 duration, .561 lift solid lifter cam and dual plane intake with quadrajet carb and headers/3" duals out the back. Just don't sink my foot in it and all is well

Matt67 · 11-10-2003, 04:07 PM

Thanks for all the replies ya'll. I get around 13 mpg with my Fords 240ci 6-cyl right now, so if I'm gonna get bad milage I'd rather do it with a V8 chevy. Of course I could go down and buy an S-10 that gets around 24+mpg, but nothing looks as cool as a lowered '72. As long as I'm not married, I'll spend the money on the cool trucks.

tom hand · 11-10-2003, 07:17 PM

I agree with Phillip Johnson...unless you have old ladies using walkers blowing past you, these trucks usally average about 10-to 12. I would think the overdrive trans will be the best bang for your buck for making it better

11-04-2003, 10:15 PM	#1
Matt67 Registered User Join Date: Oct 2003 Location: Houston, Tx Posts: 9	Average Gas Milage-V8 & V6 I was wondering what kind of gas milage you guys get with your 350/350 trucks. Please include whether it has a/c, pwr steering, lwb or swb. I want to get good milage, but hate straight 6's. I'm thinking of getting a '72 body and putting in a newer carburated V6 engine with a TH/350. Does the V6 get much better milage than a V8? Also, what different will a fuel-injection conversion, or a 700-R4, or both make? I'm sure out of all the people on this board someone will have one of these combo's. Thanks in advance, Matt __________________ Everything looks better with flames...Oh I didn't mean the engine, but whad ya expect from a Ford

11-04-2003, 10:24 PM	#2
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	I have a mildily built 325hp 350 with a TH350 in a LWB pickup....PS, PB, and 3.07 gears. The truck weighs 3980 pounds without me in it....i get about 13 mpg on average on premium fuel.....most stock 350's tend to get 10-12 mpg...if you drive easy and the engine is in good tune, 15mpg is possible on the highway. If you want to go for gas mileage.....don't buy one of these trucks. The V6 will have to work harder to pull the truck around town, so gas mileage will be only marginally better, or even the same. Plus it won't have the power and cool sound of a V8 EFI will help out quite a bit....especially if it is multipoint EFI of some kind. However...it is expensive and fairly difficult to retrofit. A 700R4 will usually pick up about 2mpg or so on the highway (from everything i have read anyway....), and would be an excellent idea if you plan to drive the truck on the highway alot. I would build a nice mild 355, add a 700R4 or 200R4 tranny, and use 3.73 gears....the truck would get an easy 15mpg on the highway if it tuned good, and have plenty of acceleration around town with 3.73 gears __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

11-04-2003, 11:33 PM	#3
BIG ORANGE Senior Member Join Date: Oct 2001 Location: Lancaster S.C. Posts: 4,767	72 swb 402/400 turbo 308 gear pb,ps,duals,600cfm holley,electronic dissy. 15mpg!!!!!!!!! OYEAHHHHHHHHH __________________ Things happen for a reason!

11-04-2003, 11:42 PM	#4
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	I haven't run the numbers officially, but I think I'm getting about -23 MPG out of my 68. Yep, that's right... I'm pretty sure I pay about $40.00 per mile (regardless if the truck actually moves or not! __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

11-05-2003, 12:54 AM	#8
StingRay Senior Member Join Date: Mar 2000 Location: Saskatoon,SK,Canada Posts: 2,476	I can get 14 mpg with a mild 350, 373 diff, th350 and cruising 70. I've also managed that at 60 with a 2500 pound flat deck (empty). __________________ Saskatoon, Saskatchewan Canada

11-05-2003, 12:48 AM	#5
Phillip Johnson Account Suspended Join Date: Apr 2000 Location: Grants Pass, Oregon Posts: 1,579	The mileage in these truck suck. once you understand that 15mpg is totally *****en and the avg is really 10 mpg, then you will be correct with the numbers that anyone claims to be getting. The best I EVER got was 15 mpg and that was in a 71 350/350 turbo with 308's on a good day. I did get 13mpg in my 72 3/4 4x4 between Chico and Las Vegas. How? I couldnt tell you. I think I had the wind behind me. The facts are, these trucks get 10 mpg. City ,Freeway, or 55mph or 70 mph.. Ive had so many of these I cant remember them all.

11-08-2003, 01:02 AM	#9
68 Suburban Registered User Join Date: Oct 2000 Location: From Chicago, Live in Phoenix, AZ Posts: 6,802	17 mpg on flat land. 350/turbo 400/3.08/HEI.

11-08-2003, 01:36 AM	#10
74Pumpkin Insert witty comment here Join Date: Nov 2003 Location: Lakeville Minnesota Posts: 388	Around 9 mpg. No ac. Short Stepside. 3.08 rear. Mild Mod on the engine. With only one of the 15 gal tanks working. I stop alot to fuel up.... With the gas prices hovering around $1.60 Well I drive the PT cruiser to work. ( I Know I Know! No egg throwing please!)

11-08-2003, 02:13 AM	#11
palallin Registered User Join Date: Jul 2002 Location: St. James, MO Posts: 1,238	My '67 SWB Fleet w/ 327/Q-jet, 4-spd Saginaw, 3:07 12-bolt was capable of 18+ on the highway, 15+ in town. Those are hard numbers, checked multiple times. Best highway mileage was a fraction over 20. __________________ '69 Longstep K-10: 327/SM465/T-221/Closed Knuckle Dana44/12-bolt.

11-08-2003, 03:09 AM	#12
Cat Fuzz My son, my joy. Join Date: Sep 2003 Location: Spokane WA Posts: 463	I have a 68 3/4 ton 2WD with some short rear end gears. Don't know exactly what ratio. I get about 12 mpg. The motor is a 327 that I used to have in a 77 Monte Carlo. That car had 2.56 rear end gears and I got 22 mpg.

11-08-2003, 03:19 AM	#13
Phillip Johnson Account Suspended Join Date: Apr 2000 Location: Grants Pass, Oregon Posts: 1,579	20 mpg with a 327..That is great

11-08-2003, 04:27 AM	#14
71-longbed Its Magically Delicious Join Date: Jan 2003 Location: oregon Posts: 2,398	i got almost 16mpg with my 350 on a 90 mile trip ..... i have 3.08's... and no AC i seriously dont care what i get around town still better than some new dodges i bet __________________ 71 C10 LWB 350sbc -TH350 12 bolt 3.42 Posi Of all my favorite things to do, The utmost is to have a brew. My love grows for my foamy friend, with each thirst-quenching elbow bend. Beer so frosty, smooth, and cold it's paradise pure liquid gold. Yes beer means many things to me that's all for now cus I gotta pee.

11-08-2003, 07:30 AM	#15
EGLIDERIDER Registered User Join Date: Oct 2003 Location: Anderson, SC Posts: 24	I have a '93 Dodge Dakota V6 w/ a 5-spd that I bought new and it's never gotten better than 22MPG on the road and about 18 in town. However, my '87 Corvette got 20+ in town and MUCH more power and that pleasing rumble. Mike __________________ All men are self made, but only the successful ones will admit it.

11-08-2003, 11:48 AM	#16
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,728	PITA to check with triple tanks, and lousy with mostly short trips. Years ago I got 11.5 mpg on a cross-country trip, K20/350/350 with 4:10s. IMO, if you want mileage in a full size truck, buy a diesel. __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

11-10-2003, 12:03 PM	#17
Hugger Registered User Join Date: Mar 2003 Location: Wichita, KS Posts: 137	I just checked the other day, not as bad as I thought it was going to be. 12.5 mpg with stock, not much done but maintenece, daily driver. 350 / TH350 __________________ 72 LWB - Hugger Orange 350/350 3.73 Next; 335hp GM Crate



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11-10-2003, 01:31 PM	#18
Green72GMC Registered User Join Date: Apr 2003 Location: Deville, Louisiana Posts: 293	I got a 305 v8 with 3.40 gears. I get 17-18 highway, I dont know what I get city. I have no a/c or power steering. swb, 1/2 ton. __________________ 1972 GMC SWB, 305 powered 1980 diesel VW pickup, Needs a Heart Transplant 1997 Toyota Taco The Second Amendment is in place incase they ignore the others.

11-10-2003, 02:25 PM	#19
bpmcgee Registered User Join Date: Mar 2003 Location: Northern Illinois Posts: 2,181	Last long trip I took I got over 13 MPG on the highway. My setup: 71 Blazer, 350. Running on 7 cylinders, it turned out (round #7 intake lobe). Unkown compression. Mild cam. 882 heads. Dynomax headers and dual 3" exhaust. 3.08 gears. SM465 tranny. Holley ProJection 2d TBI. The new engine I just dropped in has Vortec heads and a roller cam. I hope to do between 3-5 MPG better on the highway with that setup. Brian

11-10-2003, 02:41 PM	#20
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,686	9 to 10 mpg - 69 K20, when the truck was stock with the mighty 307, and 4.56 gears. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

11-10-2003, 03:44 PM	#21
ts71281 Registered User Join Date: Apr 2003 Location: Maple Grove, MN Posts: 497	My 70 SWB 468 BBC truck gets 13-15 MPG on the open road. That's with 3.73's and a 3spd on the column. My engine combo is a 9:1 compression motor with pocket ported heads with the 2.06/1.72 valves, 236 duration, .561 lift solid lifter cam and dual plane intake with quadrajet carb and headers/3" duals out the back. Just don't sink my foot in it and all is well

11-10-2003, 04:07 PM	#22
Matt67 Registered User Join Date: Oct 2003 Location: Houston, Tx Posts: 9	Thanks for all the replies ya'll. I get around 13 mpg with my Fords 240ci 6-cyl right now, so if I'm gonna get bad milage I'd rather do it with a V8 chevy. Of course I could go down and buy an S-10 that gets around 24+mpg, but nothing looks as cool as a lowered '72. As long as I'm not married, I'll spend the money on the cool trucks. __________________ Everything looks better with flames...Oh I didn't mean the engine, but whad ya expect from a Ford

11-10-2003, 07:17 PM	#23
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	I agree with Phillip Johnson...unless you have old ladies using walkers blowing past you, these trucks usally average about 10-to 12. I would think the overdrive trans will be the best bang for your buck for making it better __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

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