The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 07-05-2007, 07:58 PM   #1
WorkinLonghorn
Senior Member
 
WorkinLonghorn's Avatar
 
Join Date: Dec 2006
Location: Studio City, Calif.
Posts: 2,883
Considerations about gas mileage

I get around 12 MPG with a 350(mild RV cam,lowered compression,otherwise stock) and 4spd. Sometimes I put in $120 in a week. I was thinking these old trucks are really gas hogs. Then I did some looking around and noticed that a new Dodge Ram got 11 with the 5.7 and 12 with the 4.7 when driven around by Consumer Reports.The others got 13 or 14,none higher.And these are "1/2 ton" trucks. Mine is a 3/4 and a heavy one at that,being a longhorn on a 1 ton frame. It weighs 5200 lbs on the scales. I went on another board where the guys with the GM 3/4 tons ( 6.0 Ltr ) were getting around 12 MPG ! Sure they have tons more power available to them, but for all the fancy multi-thousand dollar computer systems,not to mention initial prices of 30-40 grand after all is included,I am looking at my old work truck in a new light.
It's built like a tank as you all know,and it is so simple and easy to repair,I really don't think I am going to miss the "heated leather seats",at least not around L.A. anyway.-Brian
__________________
'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme.
WorkinLonghorn is offline   Reply With Quote
Old 07-05-2007, 08:18 PM   #2
JimKshortstep4x4
Senior Member
 
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
Re: Considerations about gas mileage

Well said about your truck! They are great trucks and outside of gas mileage, they don't cost much to maintain.

We get 16 mpg on the highway with a 1/2 ton truck but my short step 4x4 just barely got 12 mpg on its last trip.

There are some things that can be worked on to make some improvements and there is a good article on mileage improvement in the August 07 issue of Carcraft that I believe is worth reading. I am going through my shortstep to try to get the mileage up. Even a 1 mpg improvement would help!

Jim
__________________
1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end
1965 Impala SS 400 sbc, Muncie rock crusher
1966 Impala SS 396 bbc, TH 400
1969 El Camino, 350 sbc, TH 350
1971 Snowplow built on a Blazer frame
1972 GMC Short bed, stepside, TH 400, 427 BBC
JimKshortstep4x4 is offline   Reply With Quote
Old 07-05-2007, 08:18 PM   #3
ChevLoRay
Old Skool Club
 
ChevLoRay's Avatar
 
Join Date: Jun 2001
Location: Benton, AR "The Heart of Arkansas"
Posts: 10,880
Re: Considerations about gas mileage

Not bad....mine gets about 9MPG just sitting still. I got a locking cap and drive it two or three times a month...gotta put gas in it every time I drive it.
__________________
Member Nr. 2770

'96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed.

'69 C-10 SWB; 350/TH400 - in limbo

The older I get, the better I was.
ChevLoRay is offline   Reply With Quote
Old 07-05-2007, 08:48 PM   #4
70 shorty
Where's my beer?
 
70 shorty's Avatar
 
Join Date: Oct 2004
Location: Glen Allen, VA
Posts: 1,772
Re: Considerations about gas mileage

I think what you have to look at also is not too many people can go out and lay out 40000 out of their pocket for a new 3/4 ton truck. I would think the vast majority of people that own trucks like our old ones own them outright. You can buy a lot of gas for that $600 a month or whatever the payment would be on that new truck.
__________________
70 C10, shortstep, .30 over 250,Hurst shifted 3 spd parts hauler. Holley 390, Clifford Intake, Header, ported cylinder head, unknown bigger cam.
79 Corvette L82, 4 spd, black, red interior, headers, flowmasters, and unkown bigger cam.
'03 Grand Cherokee Laredo, 4.0 4x4 daily driver. 165K miles, and runs great
'08 Tahoe LTZ 4x4 155K
70 shorty is offline   Reply With Quote
Old 07-05-2007, 09:47 PM   #5
eedgell
It's the air up here
 
eedgell's Avatar
 
Join Date: Mar 2007
Location: Western Colorado
Posts: 710
Re: Considerations about gas mileage

Yep, and the $600 a month, or what ever is for payment only. You still have to put gas in it. If you are real worried about MPG, then think about tall gears like 3:07's. That will help.
__________________
1971 cheyenne k10 4 speed np 205 454 BB factory a/c

Never drink down stream of the herd!

Eric
eedgell is offline   Reply With Quote
Old 07-05-2007, 10:07 PM   #6
'68 longbed
Registered User
 
'68 longbed's Avatar
 
Join Date: Jun 2007
Location: mississippi
Posts: 181
Re: Considerations about gas mileage

anybody ever try 3:55's in an otherwise stock truck. i used to run that in a belair and got right around 20 mpg
'68 longbed is offline   Reply With Quote
Old 07-05-2007, 10:12 PM   #7
Luvlegs
Registered User
 
Luvlegs's Avatar
 
Join Date: Sep 2005
Location: Smith Mountain Lake Virginia
Posts: 1,537
Re: Considerations about gas mileage

and don't forget insurance! My 3/4 Ram (2500)- turbo Diesel averages 16 - mostly highway everday - take the 600 payment, add ~100 insurance, AND ~100/wkfor fuel - thats $1100+ per month! The wife can't figure out why I want to drive my I-6, 72, WITHOUT AIR, daily... I like it!
__________________
"A cat will almost always blink when hit between the eyes with a ball peen hammer"
(you don't always have to state the obvious)

Wear your PPE! You can eat with false teeth but you can't see with a false eye.

1959 Studebaker Silverhawk 350/400
1972 C10 L6 3OTT
2005 F350 - Built - whew!
Luvlegs is offline   Reply With Quote
Old 07-05-2007, 10:25 PM   #8
GREASEMONKEY72
Registered User
 
GREASEMONKEY72's Avatar
 
Join Date: Aug 2006
Location: Bakersfield,CA
Posts: 7,893
Re: Considerations about gas mileage

my truck is my only vehicle and i get about 8-10mpg im not sure which but i have the stock 350/th350 and 3.07 gears with 30in tall tires, no ac
__________________
-steven
Alte Seele S.S.

"Allison" '72 C/10 LWB 350SB/TH350 - DD

PITBULL IS NOT A CRIME
GREASEMONKEY72 is offline   Reply With Quote
Old 07-05-2007, 10:59 PM   #9
HeavyD
Senior Member
 
HeavyD's Avatar
 
Join Date: Sep 2004
Location: Wakaw, Sask, Canada
Posts: 3,180
Re: Considerations about gas mileage

As far as gas mileage goes, trucks are a joke. If you can afford to spend the $$ then great, if not buy a beater for grocery getting. It won't hurt anything but your ego and you will have more cash to spend on the truck to make it even better.
__________________
"You can take the man out of PA, but you can't take PA out of the man"
HeavyD is offline   Reply With Quote
Old 07-05-2007, 11:18 PM   #10
krue
Designated A-hole!
 
krue's Avatar
 
Join Date: Mar 2003
Location: South Mississippi
Posts: 36,448
Re: Considerations about gas mileage

I drive a toy car for gas mileage, I drive my truck for work/fun.
__________________
"If it ain't broke, fix it 'til it is!"
Being stupid ain't illegal.

We're Still Debt Free Except for the House!!!
www.daveramsey.com

70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e
93 S-10 "Poppaw's Truck"
krue is offline   Reply With Quote
Old 07-05-2007, 11:46 PM   #11
ETsC10
Hand Crafted C-10
 
ETsC10's Avatar
 
Join Date: Aug 2006
Location: Burien, WA
Posts: 5,180
Re: Considerations about gas mileage

Quote:
Originally Posted by HeavyD View Post
As far as gas mileage goes, trucks are a joke. If you can afford to spend the $$ then great, if not buy a beater for grocery getting. It won't hurt anything but your ego and you will have more cash to spend on the truck to make it even better.
Well, my ego (and, just the fun of it) keeps me in my truck...got the 26MPG 1980 Escort sittin' at home. I have no other hobbies so I consider my Chevy truck addiction fairly economical.
__________________
.

Forum Guidelines and Rules
Buying and Selling Code of Conduct
Become a Board Supporter!
Truck FAQ

Ellen... the boards artsy-fartsy, eclectic, truck-lovin' gal-member...

Last edited by ETsC10; 07-05-2007 at 11:48 PM. Reason: mis-read post
ETsC10 is offline   Reply With Quote
Old 07-05-2007, 11:57 PM   #12
randomhero472
Registered User
 
randomhero472's Avatar
 
Join Date: Feb 2006
Location: oklahoma
Posts: 516
Re: Considerations about gas mileage

Im really suprised, my 06' f250 gets 15mpg... i thought it was a total gas hog! Im all about getting a scooter or little turd car to save me some $$
__________________
67' in the "build" process.. soon to be bagged, big wheels ect, finally got it back home!!

Last edited by randomhero472; 07-05-2007 at 11:58 PM.
randomhero472 is offline   Reply With Quote
Old 07-06-2007, 12:12 AM   #13
wibilly
Senior Member
 
wibilly's Avatar
 
Join Date: Nov 2005
Location: northwestern wi
Posts: 2,111
Re: Considerations about gas mileage

i got a corvette for gas miliage it's not much better than my truck but 5 mpg adds up
__________________
common sense isn't so common anymore
wibilly is offline   Reply With Quote
Old 07-06-2007, 12:14 AM   #14
GREASEMONKEY72
Registered User
 
GREASEMONKEY72's Avatar
 
Join Date: Aug 2006
Location: Bakersfield,CA
Posts: 7,893
Re: Considerations about gas mileage

Quote:
Originally Posted by wibilly View Post
i got a corvette for gas miliage it's not much better than my truck but 5 mpg adds up
now THATS a mpg car to be proud of
__________________
-steven
Alte Seele S.S.

"Allison" '72 C/10 LWB 350SB/TH350 - DD

PITBULL IS NOT A CRIME
GREASEMONKEY72 is offline   Reply With Quote
Old 07-06-2007, 01:41 AM   #15
stsalvage
Scrapper 1
 
stsalvage's Avatar
 
Join Date: Jan 2007
Location: Riverside Calif
Posts: 1,649
Re: Considerations about gas mileage

What makes a 1/2 ton diffrent from a 3/4 ton a 1 ton from 2 ton Now 3ton we almost all Know is a Flat bed a bob tail or a box truck with a 15--22 inch box or steak bed.

But getting back to the 1/2 ton to the 1 ton frames what is the diffrence.
the 1968----72 Longhorn has a 133 wheel base and the 12 foot flat beds on the 3/4 to 1 ton has the 135 wheel bases but from other then that.What makes a 1/2 to diffrent from a 1 ton Frame



NOTHING the 1/2 frame is the same as the 1 ton frame when its in a 127 inches wheel base. So that dose not effect Gas milage.

I feel the chassic is what makes the diffrence on what the truck will be the front A arms and Rear End all the sheet metal is the same on the 1/2 ton to the 2 ton trucksand so on
stsalvage is offline   Reply With Quote
Old 07-06-2007, 03:29 PM   #16
lowrollin70gmc
Too many projects
 
lowrollin70gmc's Avatar
 
Join Date: Mar 2004
Location: Fargo, ND land of the flat hills
Posts: 1,147
Re: Considerations about gas mileage

Ummm.... other than the last post, some good revelations here. I don't even want to know my truck's mileage, although it wouldn't be so bad if I wasn't always driving it like a hot rod.
__________________
Andrew
84 GMC C1500 SWB 6.2 Diesel/700R4/3.42 "Grandpa's odd duck"
70 GMC C1500 LWB My first truck: shaved, bagged, and more: the lowrollin70gmc
68 K20 Suburban 12V Cummins/NV5600/NP205/D60/11.5AAM 3.73s "Dakota Cadillac"
63 Chevy II Nova Coupe 250 I6/T56/4.56s "Economy car"
53 Willys Wagon 350/NV4500/BW4401/HP D44/9inch “Winter Wagon”
30 Model A 16 Focus ST
lowrollin70gmc is offline   Reply With Quote
Old 07-06-2007, 03:52 PM   #17
jgrh64
Prestige member Old Farts Club
 
jgrh64's Avatar
 
Join Date: Nov 2005
Location: Cleveland
Posts: 502
Re: Considerations about gas mileage

I haven't checked my mpg yet but it's at least double what my 64 gmc 305V6 4 speed was getting based on how fast the gauge moves based on a 20 mi freeway trip. It has allot to do with the tune of the engine, gearing , driving habits what brand of carburator. My friend had a '03 silverado 5.3 1/2 ton 4x4 10 mpg a $500 month payment and the last time a $600 repair bill for rough running -he sold it off and got an older less costly to repair truck without the monthly payment.
__________________
Hey sombodys gotta do it!
jgrh64 is offline   Reply With Quote
Old 07-06-2007, 03:58 PM   #18
Hook'em
Senior Member
 
Hook'em's Avatar
 
Join Date: Jul 2004
Location: Round Rock, Texas
Posts: 858
Re: Considerations about gas mileage

My 2004 Z71 Burb gets around 13 mpg. I haven't figured out the truck, but probably not much worse.
__________________
Hook'em
Hook'em is offline   Reply With Quote
Old 07-06-2007, 04:07 PM   #19
'68 longbed
Registered User
 
'68 longbed's Avatar
 
Join Date: Jun 2007
Location: mississippi
Posts: 181
Re: Considerations about gas mileage

I'm thinking a taller tire might be a half decent short term attempt to help mileage and for the tractor gears on the highway. anybody have any luck with changing to taller tires?
'68 longbed is offline   Reply With Quote
Old 07-06-2007, 04:16 PM   #20
Ackattack
Senior Member
 
Ackattack's Avatar
 
Join Date: Aug 2002
Location: Valley Center KS
Posts: 3,524
Re: Considerations about gas mileage

I've gotten 16mpg in my 72 and that was "mostly" highway driving, so I might be able to eack out 17 or 18 just strickly highway driving.

I drive my corvette to work...usually about 23mpg mixed driving. I've gotten as good as 31 out on the highway.
Ackattack is offline   Reply With Quote
Old 07-06-2007, 05:09 PM   #21
glock35ipsc
Next project: 1970 K10
 
glock35ipsc's Avatar
 
Join Date: Feb 2004
Location: Fort Collins, Colo 80524
Posts: 6,684
Re: Considerations about gas mileage

I never had the 68 running long enough to figure it out

My 03 Chevy 1500, 5.3L/4L60E was getting 18-19 on the highway. I could squeeze 20-21 on a long, steady speed road trip.

Since I installed the W4M Performance PCM in my 02 GMC 1500HD 6.0L, I went from 13.0 to about 15.5 on the highway. Towing power is through the roof!
__________________
Bob

1970 Chevy K10 LWB "Goldie" 350/TH350 next project!!
1981 Chevy C10 LWB 355/TH350 - My son's truck

LS SWAP FORUM! Tons of LS swap info here!
PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET!
CLICK HERE FOR THE FAQ INDEX by KRUE
glock35ipsc is offline   Reply With Quote
Old 07-06-2007, 05:36 PM   #22
eedgell
It's the air up here
 
eedgell's Avatar
 
Join Date: Mar 2007
Location: Western Colorado
Posts: 710
Re: Considerations about gas mileage

STOP, AND THINK! For a minute about what you all already know!!! With all of this epa, and enviromental B.S over the course of almost 50 years. They are saving the planet, better gas mileage standards. Blended fuels. With all of this junk that just ends up costing us money, because we are the consumers of all of this regulation. How far have we come in fifty years? Our old trucks run with the newest of them, mpg, with all of this regulation to make them more fuel efficient, and more enviromentaly "friendly". They havent done jack in 50 years, but cost you and me alot of money. Old technology works just as good as new. 50 years worth. What good to the enviroment or your pocket book has the computer age been? According to the 50 years of hype, by now we should be driving our cars for free.
__________________
1971 cheyenne k10 4 speed np 205 454 BB factory a/c

Never drink down stream of the herd!

Eric

Last edited by eedgell; 07-06-2007 at 05:43 PM.
eedgell is offline   Reply With Quote
Old 07-06-2007, 05:44 PM   #23
Billy Ol' Blue
Registered User
 
Billy Ol' Blue's Avatar
 
Join Date: Apr 2007
Location: Acworth, Ga
Posts: 27
Re: Considerations about gas mileage

My 72 longbed is a daily driver it get 16 mpg or 15.5 gallon tank a week 350 5.7 - 3 speed auto 4x4 600 cfm holley with vacum sec.
Billy Ol' Blue is offline   Reply With Quote
Old 07-06-2007, 05:49 PM   #24
Robert1970C20rstbukt
Registered User
 
Robert1970C20rstbukt's Avatar
 
Join Date: Jun 2004
Location: Beeville, Texas
Posts: 1,943
Re: Considerations about gas mileage

I've been getting about 15MPG with the truck(no BS), that was city and highway driving and I fill it up once every two weeks. I never drive faster than 50-55 on the highway. The low mileage rebuilt 307 swap and HEI ignition upgrade helped a lot. I wanted to keep the 4bbl Quadrajet so we swapped manifolds and carbs from the blown 350 on to the 307. The transmission(1967 TH400) is stock and the rear axle has 4.10's with 33x12.50 tires. Not bad for a 5100lb truck! I don't even wanna know what my Suburban would get..................
__________________
RJD

1984 Chevrolet C30 welding truck 454/SM465
1977 GMC C15 pickup 350/TH350
1970 Chevrolet C20 pickup 350/TH400
1970 Chevrolet K20 Suburban 454/TH350
1969 GMC 8500 478M V6/5 spd winch truck
Robert1970C20rstbukt is offline   Reply With Quote
Old 07-06-2007, 06:32 PM   #25
mnunn454
Registered User
 
mnunn454's Avatar
 
Join Date: Dec 2006
Location: Rhode Island
Posts: 602
Re: Considerations about gas mileage

To improve mileage may I suggest any/all of the following:

- Dual Exhaust with low restriction mufflers. (Plus Long tube headers if that's attractive to you.)
- You need a final drive ratio in the 2.5 to 2.8 to one range with normal 28" tall tires. If your tires are 10% taller than that, then maybe 2.8 to 3.0 to one would be about right. Highway engine RPM should be in the 2000 to 2200 range. Several ways to achieve this of course, Bolt on Overdrive, Change the ring and pinion, change to an overdrive tranny. R&P swap is the least expensive, but may hurt your 1st gear/takeoff performance.
- Measure the air/fuel ratio at normal cruising speeds. It should average in the 14.5 to 14.6:1 range. If it's not (it's probably in the 13.0:1 range), lean the idle and air-bleed circuits (not the main jets) of the carb until you get 14.6:1.
- If you don't have HEI ignition, get one. They're great.

- Make sure the timing is set as far advanced as you can run it, given the grade of gasoline you buy. Back it off one (1) degree at a time until it stops pinging. You may be able to have the distributor "recurved" to better fit your application, and eliminating a lot of the pinging.

- Add an MSD box (Multiple Spark Discharge) if resources allow. It sparks multiple times per cylinder stroke at anything under 3000 RPMs (which is where you'll be once you get that 2.7:1 final drive ratio.

- Pull the mechanical cooling fan and install dual electric puller fans with a shroud. It'll save about 12 horsepower which translates to about 5% of your engine's output at highway speeds.

Do "all the above" and you could get 16-17 MPG which translates to about a 30%-40% boost in mileage and an equal reduction in your gas bill.

JMO. Best wishes.
__________________
69 C-10 SWB Fleetside 454/TH400 (For Sale)
http://67-72chevytrucks.com/vboard/c...ct=1299&cat=12
70 El Camino 454 TH700
29 Model A 4-DR Sedan Deluxe

Last edited by mnunn454; 07-06-2007 at 06:34 PM.
mnunn454 is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 03:16 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com