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#1 |
Registered User
![]() Join Date: Jun 2014
Location: Houston, Texas
Posts: 722
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tips for better MPG
I know these trucks are not bought for their fuel efficiency, but I'm getting between 7-9 mpg per tank. My truck needs a new sending unit, so Im having to watch the miles instead of gas gauge. I got 109 miles down with 14.3 gallons burnt LOL
Any tips on getting a little better MPG out of this thing? I've recently done a full tune-up, converted to electronic ignition, got the timing right, changed the oil, air filter, PCV value, tire pressure is good....any other things I can do? Again, I don't really care about the gas mileage, this is not why we drive these beasts but if I can save some extra $$$ that's more that I can dump back into her! |
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#2 |
Registered User
Join Date: Apr 2014
Location: CA
Posts: 27
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Re: tips for better MPG
Stay out of the secondaries. Lead foot eats mileage.
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#3 |
Registered User
Join Date: May 2014
Location: Sacramento CA
Posts: 60
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Re: tips for better MPG
a big ole turbo with a long spool would help
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#4 |
Registered User
Join Date: Feb 2012
Location: Mission Viejo, CA
Posts: 1,856
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Re: tips for better MPG
put it in neutral going down hills.
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#5 |
Registered User
Join Date: Jul 2008
Location: Bowie, MD
Posts: 313
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Re: tips for better MPG
Buy a wideband O2 sensor, an adjustable vacuum advance, and get to tuning. Your cruise AFR should be about 15:1 for a safe tune that will get you decent MPG, probably on the order of 50 degrees total advance at cruise (initial + mechanical + vacuum). Those are, of course, ballpark numbers.
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#6 |
Registered User
Join Date: Mar 2012
Location: New Orleans, La
Posts: 406
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Re: tips for better MPG
I've done a lot of research on here and most of the tips are going to be for better highway mileage for instance HEI (I squeezed out 1 1/2 mpg better highway), headers (supposedly), rear end gears (the debate's still going), electric fans, etc.
Apparently the only way to really see any gain is to drop in a newer style injected engine. Even then, the front end of these trucks limits any large mpg gains. I have seen where someone said that lowering the truck gave him some better mpg.
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It's not that I am apathetic, I just don't care. If your life is a joke, it appears death will be your punchline. |
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#7 |
Registered User
Join Date: Jun 2010
Location: Upland Ca
Posts: 4,143
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Re: tips for better MPG
If you have a quadrajet I would be getting it rebuilt by a professional (SMInduction or Ruggles). If your speedo is off as far as mine you might be getting more than you think.
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1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703 |
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#8 |
Registered User
Join Date: Dec 2006
Location: Porter Ranch, CA
Posts: 978
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Re: tips for better MPG
Check the accuracy of your speedo as suggested above. And then I'd look at the carb for an underlying problem. You should at least get double digit mileage.
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#9 |
Registered User
Join Date: Feb 2011
Location: Modesto, CA
Posts: 2,188
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Re: tips for better MPG
A vacuum gauge can help you manage your fuel efficiency. Also, what trans and rear gears do you have? A cheap swap to OD be it auto or manual can net a few more mpg's at higher speeds if you can make it cost effective. Less weight helps, as well as lightening the rotating mass but that usually costs much more than it saves. A properly tuned engine in good working order really is your best bet. Any reduction in friction helps too, but again, more money than gains.
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#10 |
Account Suspended
Join Date: Jan 2007
Location: Tucson
Posts: 2,183
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Re: tips for better MPG
One of these will fix your MPG problem really quick!
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#11 |
Hittin E-Z Street on Mud Tires
![]() Join Date: Nov 2004
Location: Greenville, SC
Posts: 23,090
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Re: tips for better MPG
Engine/trans/axle ratio. Carb set up too. 7-9 is pretty horrible, unless you have like a big block 4.56 geared truck. I got 11 with my 250/3spd/3.73 and I romped on the poor girl (was 16 at the time).
I now have a 350/700R/3.73 and get 12 around town and 16 highway. Have you used a GPS to verify miles?
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Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride ![]() American Born, Country by the Grace of God ![]() 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications! |
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#12 |
Registered User
Join Date: Dec 2011
Location: winnipeg
Posts: 1,107
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Re: tips for better MPG
Other then a ls swap or a od trans it's really a matter of fine tuning as said before but it's really not going to be stellar no matter what. Even 15 mpg is a pig to drive in this day and age. I get no where near that myself either. I reside myself to the fact if I want to get good Mpgs with my truck I leave it shut off in the driveway. My neighbour installed a gear vendors od unit in his f100 hoping for 18 Mpgs in the city and it came close but all said and done it was $4000+ To get it done.
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#13 |
Registered User
Join Date: Dec 2006
Location: Porter Ranch, CA
Posts: 978
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Re: tips for better MPG
Also can we get some details as to what engine/tranny you have, what rear end gears, tire size? Maybe some of us can give you a ballpark of what MPG to expect based on your set up...
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#14 |
Senior Member
![]() Join Date: Jul 2012
Location: Knoxville, TN
Posts: 499
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Re: tips for better MPG
In my 71 with a 350 three-speed and 3.07 gears, I got 13 mpg combined. I probably will get slightly better this week since last I blew a tire off and limped to the nearest safe spot. In reality I don't expect better than 15 or so for the simple fact that it is a truck. My 93 tbi 4.3 Sierra only gets 15.
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1971 Chevy C10 Cheyenne (sold for Mazda) 1963 Chevy Corvair Pro-Touring Project 2012 Mazda 3 i Sport sedan http://www.dracoautodesigns.com/ |
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#15 | |
Registered User
Join Date: Dec 2006
Location: Porter Ranch, CA
Posts: 978
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Re: tips for better MPG
Quote:
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#16 |
Registered User
![]() Join Date: Jun 2014
Location: Houston, Texas
Posts: 722
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Re: tips for better MPG
Well I downloaded an app on my phone to check the odometer and it's accurate within a tenth of a mile, so that's not the issue.
I'm running a stock 350 engine (with the exception of a newly added Edelbrock 600 CFM performer series carb and air cleaner) and running though the stock TH350 transmission....I'm not sure about the rear end gears. I'd assume they are whatever came stock on a 72 C20 custom camper with 350 engine and TH350 trans. I've ran through 3 tanks of gas since I bought her, first tank was 8.23 mpg, 2nd was 9.4 and 3rd was 7.6 |
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#17 |
Registered User
![]() Join Date: Jun 2014
Location: Houston, Texas
Posts: 722
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Re: tips for better MPG
first tank was on the stock quadrajet (needed rebuilding badly) other two tanks where with the edelbrock. 2nd tank was before tune-up, and 3rd was after tune-up.....so I've got my worst mpg after doing the tune-up LOL
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#18 |
Registered User
Join Date: Jul 2008
Location: Bowie, MD
Posts: 313
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Re: tips for better MPG
Do you have a working exhaust crossover, thermostatic air cleaner and functional heat stove, functioning vacuum advance, and functioning thermal fan clutch?
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#19 |
Senior Member
![]() Join Date: Jul 2012
Location: Knoxville, TN
Posts: 499
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Re: tips for better MPG
What do you gain from the fan clutch? I know that you should pick up a couple of horse and maybe some mpg but I have never seen any data from it.
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1971 Chevy C10 Cheyenne (sold for Mazda) 1963 Chevy Corvair Pro-Touring Project 2012 Mazda 3 i Sport sedan http://www.dracoautodesigns.com/ |
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#20 |
Registered User
Join Date: Jul 2008
Location: Bowie, MD
Posts: 313
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Re: tips for better MPG
Spinning a mechanical fan at 100% draws a lot of power, plus it slows down your warm up time if you don't have the thermostat type.
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#21 |
Senior Member
![]() Join Date: Jul 2012
Location: Knoxville, TN
Posts: 499
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Re: tips for better MPG
Is there a noticable diffence in milage or horsepower to warrent the time and expense of a conversion? I know the theorical result but I have not ever seen something to back it up. I don't want to put the money into a fan clutch if it will give minimal results.
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1971 Chevy C10 Cheyenne (sold for Mazda) 1963 Chevy Corvair Pro-Touring Project 2012 Mazda 3 i Sport sedan http://www.dracoautodesigns.com/ |
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#22 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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Re: tips for better MPG
Stock you should get at least 10-12 MPG in a city/hwy mix. None of these little things will make up the 3-4 MPG but maybe all of them together might, hard to say.
Probably the best investment would be to weld in an O2 sensor bung and run a gauge for a while. Has to be a wide-band of course. You'll see if its rich at cruise, at what speeds, at what loads, and so on. Then you can tune the carb. Of course the carb has to be RIGHT beforehand. Ruggles would be nice, but he was 6+ months out last I checked. Carb Connection in Kirkland WA talks the talk, but I haven't driven the car with it yet.
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#23 | |
Registered User
Join Date: Jul 2008
Location: Bowie, MD
Posts: 313
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Re: tips for better MPG
Quote:
I don't have any valid scientific data for you. I can tell you that turning that big old fan sure seems to take a lot of effort. I am in the process of replacing the flex fan on mine with a fan clutch, but at the same time I am replacing the exhaust, changing out the points for an electronic module, changing the carb and intake, and adding the heat crossover valve to the exhaust. I expect all of that to make a substantial difference in fuel economy once it is all said and done, but I will never be able to quantify how much difference the clutch fan itself makes given all the other changes. |
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#24 |
Registered User
Join Date: Jun 2011
Location: United States
Posts: 158
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Re: tips for better MPG
I got 21mpg in my '68 longbed with a 307ci backed by a T5 transmission. Holley Avenger EFI setup, MSD Pro-Billet distributor, 3.73 rear gear, 27-inch tire. That's highway, city was around 18 or so. I would think that's about as good as it gets using a SBC and not doing a bunch of drastic things.
I think the easiest and biggest improvement would be either an OD trans and/or an EFI setup like the Avenger. Bolts right up to a four barrel intake manifold. Wonder what some of the LS setups are producing when it comes to MPG? |
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#25 |
Newbee
Join Date: Jan 2010
Location: Phoenix, Arizona
Posts: 1,406
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Re: tips for better MPG
A while back, I saw some dyno numbers that had a fan pulling 20+ HP. FWIW
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