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#26 |
Senior Member
Join Date: Nov 2004
Location: Vacaville, CA
Posts: 2,272
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Re: Need to improve mileage!
I only get 15MPG in my Avalanche and that is with overdrive and fuel injection. I am getting about 18 with my 67 extended cab truck with a 91 TBI motor and a 400 trans with 3.07 rear gears.
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#27 |
Registered User
Join Date: Feb 2009
Location: Southern Oregon
Posts: 1,352
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Re: Need to improve mileage!
16.5 mpg or thereabouts was the best mileage I ever got with my 69 C10 when I had a 250 6 cyl. in it wth 3.73's. This was cruising at 60 mph on flat interstate. I have heard of some guys on here approaching 18mpg highway with a 250 and overdrive in a 2wd. As far as the original poster's question I would suggest a Q-jet carb for the best fuel economy if not already running one. I went fom a quadrajet to a carter 625 on my old Chevelle and lost 2 mpg. You might also consider a narrower tire. I'm assuming your 32's are 11.5 wide. BFG as well as others make a 33/9.5/15. May be something to consider if your in the market for tires any time soon. I've heard synthetic oils in all diffs and gearboxes help as well, though I wonder how much.
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1967 C10 Suburban 454/TH400/3.07's An Average Joe and His 'Burb: http://67-72chevytrucks.com/vboard/s...d.php?t=775843 |
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#28 |
Registered User
Join Date: Dec 2009
Location: DFW, TX
Posts: 764
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Re: Need to improve mileage!
What year Av? I only get 14 out of my 07 Avalanche. I got 16 MPG out of my 04 Avalanche. The 72 only gets 12.
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72 Cheyenne Super 1/2 LWB White/Dark Yellow 07 Avalanche 2LT 74 Sleek Craft Rebel Jet Boat W/Pontiac 400 Last edited by OhOneWS6; 12-19-2009 at 11:59 PM. |
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#29 | |
70 Chevrolet=Obsession
Join Date: Jun 2009
Location: nice ca
Posts: 1,067
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Re: Need to improve mileage!
Quote:
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![]() ![]() ![]() I'm Just like my truck. Old, Ugly and Grouchy. Except my truck starts easily in the morning and doesn't smoke! IT'S NOT EASY BEING GREEN! -Kermit the frog 1970 Chevrolet C-10 Longbed Stepside : 350, Muncie M20, 3.08 GM corp. positraction Forest green exterior/light green interior(Where all my money goes) 1996 Toyota Corolla (Parts runner) Last edited by unclewatts; 12-20-2009 at 04:38 AM. |
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#30 |
Registered User
Join Date: May 2009
Location: Eliot, Maine
Posts: 1,314
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Re: Need to improve mileage!
no big blocks
2wd is better on mileage than 4wd (saves weight, less moving parts) softer gearing (no 4.56's) overdrive - 700r4, 5 or 6 speed etc. i bought my 72 burb because it 2wd because i love the looks and ride of the all coil suspension on these trucks. i won't be doing much winter driving and burbs have better traction than pickups anyway. my truck wieighs a bit more because it is a 3/4 ton but probably still less than a 1/2 ton 4x4 because most of the extra mass is in the springs, trailing arms, etc....not a big beefy front axle. it makes oil changes easier too. i am converting the ho52 from a 4.57 to a 4.10 gear which will get me a 10% drop in rpms. that means that the difference will be almost nill at a slow crawl, but the faster i go, the more rpm's i'm saving. i also want to add the factory overdrive to the saginaw 3 on the tree but the few of those out there are demanding very high prices.....$350 for a rebuildable core on ebay just recently. |
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#31 |
English Chevy Owner
Join Date: May 2002
Location: Shropshire, UK/ Lot, France
Posts: 1,848
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Re: Need to improve mileage!
I ran my truck as my daily for a couple of years but with gas prices the wya they are over here (at their peak around $8/US Gallon) it just wasn't practical. I now have a 98 Isuzu Trooper with a 3.1L turbo diesel that gets mid twenties and the wife has a Nissan X-Trail company vehicle that gets mid 30's.
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Phil '67 C10 long fleet. 350/TH350, 4 bbl Carter, K&N, Dual exhaust, loads of stuff coming soon 2001 S10 Blazer Daily Driver, bone stock 4 door 4x4 with manual transmission |
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#32 |
Future TOTM Winner
Join Date: Aug 2006
Location: Bulverde, TX
Posts: 2,692
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Re: Need to improve mileage!
You hit the nail on the head.
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72 Chevy CST K5 HIGHLANDER BLAZER Getting a 6.0,NV4500,NP205,14BFF (Currently laying all over the place in little pieces) 72 Chevy swb step-side "LS" 6.0 Here's a build thread of sorts 2002 HD2500 Crew Cab, 8.1L Allison 4x4 Daily Driver Check it out www.lsdyno.com |
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#33 |
Senior Member
Join Date: Nov 2004
Location: Vacaville, CA
Posts: 2,272
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Re: Need to improve mileage!
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#34 |
Account Suspended
Join Date: Dec 2008
Location: indisclosed
Posts: 1,515
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Re: Need to improve mileage!
Here's a scrap of info that i just picked up that might be a cost-effective solution for your problem:
Try putting 305 heads on your 350; It will raise compression which equals better mileage and power. At least low-end power. As you probably know, 305 heads can be gotten cheap if not free. Last edited by C-10 simplex; 12-20-2009 at 03:03 PM. |
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#35 |
Registered User
![]() Join Date: Jan 2001
Location: Sabinal, Texas
Posts: 1,706
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Re: Need to improve mileage!
My '72 402/4-speed gets 10-13 around town and maybe eek out 15 on the hwy. Tried EFI--gained 1-2 MPG but still this truck is about as aerodynamic as a brick. Youre stuck with the mileage. But for the WOW factor it is worth it taking in the shorts at the pump. Folks love seeing my '72 with a big-ass Lance camper strapped to the ass-end..especially when I out perform the newer ones up a grade!
I would'nt change it. I have my "daily" driver for gas mileage. I use this truck for hauling stuff and summer vacations. --Bud |
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#36 |
Senior Member
![]() Join Date: Feb 2003
Location: Gold Canyon Arizona
Posts: 4,355
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Re: Need to improve mileage!
the way i see it is we all! stop at the station sooner or later.. so just buy a bigger tank...
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1971 K5 CST Blazer 1951 -3100 5 window short bed 4sp 1965 Chevelle Malibu 283 (sadly sold) 1968 Camaro 327 1968 Honda mini-trail z50a #377 1966 uh 1-D Huey |
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#37 |
Account Suspended
Join Date: Dec 2008
Location: indisclosed
Posts: 1,515
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Re: Need to improve mileage!
The other thing that i wanted to touch upon, (but i don't have time to investigate whole-hog right now, but in the meantime consider these)was, let's see what we can do first to save on gas without even considering the truck. Without opening the hood, making modifications etc.
For example, i think Discover has a credit card that refunds 2% on all gas purchases. i'm pretty sure shell and BP also have similar. i think american express has one that refunds 4% on gasoline purchases. It has an annual fee though, so we need to take that into consideration. Probably still worth it. Again, i don't have time to get into it whole-hog, but my strategy would be to try to first do anything/everything you can to save on gas, then maybe make modifications to the truck. i think it has to do( i know it does for me) more about money than actual mpg; If gas were .35 cents a gallon, would anyone give a crap about mpg? Last edited by C-10 simplex; 12-20-2009 at 04:55 PM. |
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#38 |
Registered User
Join Date: Dec 2007
Location: Santa Maria, Ca.
Posts: 1,423
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Re: Need to improve mileage!
I pay cash for my gas as at most places in Calif its 4 or 5 cents cheaper with cash
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69 Chevy 4x4 383 Power ![]() |
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#39 |
Account Suspended
Join Date: Dec 2008
Location: indisclosed
Posts: 1,515
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Re: Need to improve mileage!
Yeah, that too---cash may be cheaper than credit card at some stations.
Also i think Speedway sold/sells gift cards worth $50 for $48 or something like that. So if you bought that using another credit card that pays % refund, then this could be a substantial savings. There's a whole world of savings concerning gas that don't even involve the car. i do not, presently, have time to investigate this world. Last edited by C-10 simplex; 12-20-2009 at 11:18 PM. |
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#40 |
Senior Member
![]() Join Date: Aug 2004
Location: Centennial, CO
Posts: 2,956
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Re: Need to improve mileage!
I'd say go EFI, but the $ difference isn't that much when you do the math. I got 2mpg out of my TBI.
Now if you consider the cold start driveability, it's a whole new world.
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ClusterTruck: 68 C10 Bought in 89, wrecked in 03. Slow low $ rebuild started '17. 6.0 & TKO http://67-72chevytrucks.com/vboard/s...d.php?t=788602 93 K1500 Short Step, 350, NV4500, EBL flash ECU. Vortec heads & roller cam someday... 05 Jeep Wrangler Unlimited. 3” lift & 6-speed 02 E320 the insurance total “free car” 13 Tahoe LTZ |
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#41 |
Registered User
Join Date: Oct 2005
Location: Northern Arkansas
Posts: 1,136
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Re: Need to improve mileage!
How about Hydrogen On Demand? My neighbor bought a '97 Lexus 4X4. It's just like a Toyota Landcruiser. It has 170,000 on it, and a 4.3 24valve inline 6. He was averaging about 13.5 mpg everyday driving. I have always wanted to try the HHO systems but have been very skeptical. He called me up one day and told me he had a Hydrogen system coming, and asked if I'd hook it up. So, after a couple of evenings (about 6 hours) it was installed and operational. The toughest part was finding a place to mount the equipment under the hood of that thing. Anyway he now averages 16.5mpg for about a $400 investment.
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#42 |
Registered User
Join Date: Sep 2008
Location: Salem Oregon
Posts: 63
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Re: Need to improve mileage!
the best i ever got with 3.07 ratio is 15.8 mpg on the freeway ... i haven't checked the mpg since the 3.42's went in ....
it amazes me that a carbed 40 year old truck get only afew mpg less then a computer controlled newer truck ... theres not much evolution there
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350/th350 Sportsman2 heads Performer Intake 1406 carb 3.42 Eaton Posi |
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#43 |
Registered User
Join Date: Mar 2007
Location: San Pedro River, SE Arizona
Posts: 734
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Re: Need to improve mileage!
It's all been said in this thread - many practical suggestions for improved MPG and some good analysis of cost/benefit over time. A big factor seems to be psychological - that we rarely have to repair or modify our trucks, but we regularly have to go to the pump, so we get frequent reminders of our fuel cost and consumption. My reason for having all of these old Chevs/GMCs is that THEY WORK, they are fun and they look wonderful. The difference in MPG between the lightest and heaviest is minimal and that comes with this series truck. On some I can get 14 MPG which seems pretty good, but the C30 with 402BB and a HEAVY chassis mount motorhome camper will get 12 MPG if I take it easy, and we drive it all over the US. Of course it looks old fashioned and ugly to some (some of my kids live in rather fancy neighborhods, but I still park it in their driveways) and even though we could own a much bigger modern motorhome with all the fancy stuff - this is my choice because I like to drive it and it feels great. You might be surprised how many knowing smiles, compliments and offers to buy it on the spot I get every time we venture cross country. So, the higher fuel consumption is one of the costs of love and distinction. There are much higher costs being paid in life.
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CCCC 67 Sting Ray Coupe 327 4sp; 68 K10 Suburban 327 4sp; 69 K20 Lifted 383 4sp; 69 C80 Fire Truck 478 V6 5sp/2sp; 69 C20 Longhorn 327 4sp; 70 C30 Wrecker 350 4sp; 70 C30 Flat Bed 350 4sp; 71 C20 LWB 350 4sp; 72 K5 Blazer 350 4sp; 72 C30 Flat Bed Gooseneck Hauler with sleeper 350/TH400; 72 C20 Longhorn 402 4sp; 52 Mack LTL Supercharged Cummins 5sp x 3sp; 01 Dodge 5.9 HO Cummins 6spd; 02 Safari Trek 2430 8.1 Vortec on Workhorse Chassis; 03 Silverado 2500 HD 4wd Duramax/Allison Moved but still in the family 70 C20 Custom Camper 350/TH350; 72 K5 Blazer CST Highlander 350/TH350 Recently sent to new homes 72 C30 MoHome 402 4sp; 72 K5 Blazer Conv 350 4sp; 75 GMC 6000 Aerial 350 w Allison; 72 GMC 3500 Utility 350 4sp; 70 GMC 3500, 350 4sp |
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#44 | |
Future TOTM Winner
Join Date: Aug 2006
Location: Bulverde, TX
Posts: 2,692
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Re: Need to improve mileage!
Quote:
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__________________
72 Chevy CST K5 HIGHLANDER BLAZER Getting a 6.0,NV4500,NP205,14BFF (Currently laying all over the place in little pieces) 72 Chevy swb step-side "LS" 6.0 Here's a build thread of sorts 2002 HD2500 Crew Cab, 8.1L Allison 4x4 Daily Driver Check it out www.lsdyno.com |
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#45 | |
Registered User
Join Date: Mar 2008
Location: Lafayette, IN
Posts: 226
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Re: Need to improve mileage!
Quote:
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Mark 1967 C/10 stepside lwb daily driver 1968 C/10 fleetside lwb parts truck 1971 Cheyenne Super swb project |
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#46 |
I make Models
![]() Join Date: May 2005
Location: Bucks, PA
Posts: 626
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Re: Need to improve mileage!
Headers with a good flowing exhaust and electric fan (removing the stock one) would get you a little more mpg.....jmho
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#47 |
English Chevy Owner
Join Date: May 2002
Location: Shropshire, UK/ Lot, France
Posts: 1,848
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Re: Need to improve mileage!
After the Copenhagen summit this might be a conversation more of you will have! Its already an issue over here with larger engined vehicles facing fairly hefty tax penalties both at purchase and annually with hybrids and small efficient cars getting various tax breaks. Many smaller cars here will now do in excess of 50mpg.
__________________
Phil '67 C10 long fleet. 350/TH350, 4 bbl Carter, K&N, Dual exhaust, loads of stuff coming soon 2001 S10 Blazer Daily Driver, bone stock 4 door 4x4 with manual transmission |
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#48 | |
Registered User
Join Date: Feb 2000
Location: Center City, MN, USA
Posts: 3,254
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Re: Need to improve mileage!
Quote:
Assuming this alleged global warming is man made, why won't this far left wing government that is driving us daily towards all out socialism, allow the US automakers to build a car with a small, turbo charged deisel engine? Everybody knows these smaller cars with turbos and direct injection and manual transmissions get 50+ mpg. Why won't our government and the executive branch push for such vehicles? We all know the answer but this isn't a political forum it is a car forum and this is a post about 50+ mpg cars, not soalistic left wing governments trying to control your life through higher fees and taxes.
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'70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN |
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#49 |
Senior Member
![]() Join Date: Dec 2009
Location: Culpeper, VA
Posts: 434
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Re: Need to improve mileage!
Back in the early eighties, a friend of mine bet me a case of beer that he could get my 2 wheel drive '72 blazer to get over 25 mpg. I was running a 305 with 296 valved heads, 4 barreled with headers.Thinking I had a free weekend of beer coming to me , I took him up on it. Not that I'm condoning this, but he pulled the blazer in his garage and pulled the 4 nuts and studs holding the carb down. Then he went over and after rummaging around, pulled out a piece of stainless steel door screen and cut a piece a little larger than the quadrajet. Next he sandwiched it between my carb gasket and another gasket he had hanging on the wall.
Long story shorten..... 29 mpg and more power! Seems the theory was that the gas hits the slightly heated screen and vaporizes. Gas vapors burn easier than gas liqiud. Supposely, someone came up with this theory back in the '60s and the oil companies bought the patented idea...... so he said. All I know is I was out a case of beer! |
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#50 | |
Future TOTM Winner
Join Date: Aug 2006
Location: Bulverde, TX
Posts: 2,692
|
Re: Need to improve mileage!
Quote:
__________________
72 Chevy CST K5 HIGHLANDER BLAZER Getting a 6.0,NV4500,NP205,14BFF (Currently laying all over the place in little pieces) 72 Chevy swb step-side "LS" 6.0 Here's a build thread of sorts 2002 HD2500 Crew Cab, 8.1L Allison 4x4 Daily Driver Check it out www.lsdyno.com |
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