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#1 |
Registered User
Join Date: Oct 2007
Location: Wendell, Idaho
Posts: 608
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Way to improve fuel economy??
So yesterday I went to the hills again toget a load of wood. I put the gps in the truck cause I wanted to get a good estimate on my fuel mileage. I put 184 miles on the truck, not freeway, but back country roads, up and down in the mountains, I bet 40% was in 3rd gear at about 30 mph.
Here is the deal, I have a 327 with upwards of 170000 miles on it, a sm420/221 combo, 4:10 gears. It is a 3/4ton 4x4. Single exhaust aslo. The motor has good compression, 2 cyclinders have 150lbs and the others range 145 down to 130lbs. I run a quart of lucas oil every oil change, dont know if this helps or not, it may just be mental for me. On this trip I got 9.3 mpg. Not great, but what gets me is last year I had 3:07 gears and got 9.7 mpg on the same trip, going almost exactly the same places. Does anybody have any ideas for better gas milage? I mean at 9 mpg I could almost justify putting int he 396 I have and have more power. I havnt done it cause I didnt want to drastically change my milage, but I am wondering if it matters at this point.
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1969 4x4 Nothing beats a good rock drill and some dynamite |
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#2 |
Registered User
![]() Join Date: Oct 2005
Location: Sacramento, CA
Posts: 1,970
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Re: Way to improve fuel economy??
By today's standards, bad mileage, but given an old heavy 4x4 with aggressive gearing and a good old fashioned carbed small block.....that mileage probably isn't too bad. Headers and duals would help some and you didn't mention what carb you had, but a small (600cfm) spreadbore type would probably be best. Fuel injection would be of some benefit, but by the time you figure the cost of that, you're probably best off to do a late model 5.3 swap.
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72 Cheyenne SWB Fleet Nut & bolt frame off in progress...99.9999% - supercharged 383 - 4 wheel discs - relocated fuel tank - ![]() My Build Thread |
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#3 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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Re: Way to improve fuel economy??
get your wood delivered you'll get better mileage
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71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY |
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#4 |
Registered User
Join Date: Apr 2010
Location: Russiaville
Posts: 203
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Re: Way to improve fuel economy??
It takes torque to get a load moving, a 327 is not a good torque motor. Low speed, starting and stopping, hills, all hurt mileage. The reason that all stated fuel mileage estimates are much lower for city driving is because it takes so much energy to get the load moving, but once its at speed, it doesn't take so much.
Its all a compromise, if you did build a motor that got good mileage, it would suck at hauling, if you build for hauling, it will suck for mileage. Yes, you can put a diesel in it, put in an overdrive transmission, which has a better first gear ratio, fuel injection........but the cost will eat up your savings. BTW:a lower first gear ratio helps very little if your not in overdrive, and if you put the 3:07 gear back in, the engine will lug in overdrive, and you will gain nothing. You could buy a newer truck, but there again how long do you have to drive it before you actually start saving money. Or you can accelerate VERY SLOWLY, which takes forever, (at least for people as impatient as myself ) and watch very carefully that you don't try to accelerate while going up hill. (of coarse, most cities built the intersections as the low point for drainage, so your almost always accelerating up hill)
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......its not what your askin', its what your gettin'.... .......every time I screw up, I learn something. Needless to say, I'm learning all the time............ |
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#5 | |
Registered User
Join Date: Oct 2007
Location: Wendell, Idaho
Posts: 608
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Re: Way to improve fuel economy??
Quote:
I figured that the milage is just what it is, like you said SactoJim, its old heavy and 4x4 so it isnt an econobox, I just didnt know if there was anything I could do to boost the milage a little. I am thinking getting rid of the points ignition and upgrading to HEI, I think that may help a little. The carb is the stock Q- JET, I have an edlebrock 600 that I should put on. I also need to dual exhaust it, just need to figure out best routing for the pipe along the tcase. I would like to eventually go with the 396/nv4500, but not right now. Which is better, 396 or 454 for torque. I have a 396 is the only reason I am thinking along that line. Hauling 5600 lbs of wood hurts the milage a bunch, but it also gives me heat in the winter and the extra is a little cash in the pocket. Im just fishing for ideas I guess.
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1969 4x4 Nothing beats a good rock drill and some dynamite |
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#6 |
Registered User
Join Date: May 2005
Location: Bowling Green, Mo
Posts: 204
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Re: Way to improve fuel economy??
It's a 3/4t. How much are you willing to spend to get a couple extra mpgs, being a 4x4 its not gonna get much better than 12 -14 mpgs being 3/4t also. A 327 is a great motor. But it doesn't fit the situation.
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1978 GMC K25 2002 Dodge Dakota R/T rc swb In need of some more goodies. |
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#7 |
Registered User
Join Date: Apr 2010
Location: Russiaville
Posts: 203
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Re: Way to improve fuel economy??
6 blocks?! That not even enough time to get the engine warmed up. I doubt that the choke has even opened up completely by the time you arrive to work.
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......its not what your askin', its what your gettin'.... .......every time I screw up, I learn something. Needless to say, I'm learning all the time............ |
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#8 |
Senior Member
![]() Join Date: Oct 2009
Location: Godley, TX
Posts: 17,963
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Re: Way to improve fuel economy??
I would submit that any drive that includes going up and down hills and 3rd gear only 40% of the time is not only going to be low (and that's ok, it's expected to be low in that scenario), but it's also going to be difficult to compare to something else just because you're constantly on/off the gas, up/down hills, etc. It is a data point, but not a real useful one.
I would say that if you want to compare configurations - the only apples to apples comparo will be highway mileage. Preferably interstate-non-stop at reasonable speed. Of course it will be higher mpg because it's highway, but at least then, the only variable is the changes you make to the truck, not the possum you dodged (or accelerated to hit) in the hills on the first trip and not on the 2nd trip. Considering your configuration, especially the rear gear, 9.anything is very respectable. Don't get me wrong, I do understand your question is - what to do to get BETTER mileage, regardless of what it is now. So, I'd ask this - 1. do you "need" a 4.10 rear gear? 2. If you have 170k on the truck, what shape is the trans in? i.e. if it COULD be construed that it's time for a rebuild (or if you can convince yourself of it in order to justify the idea) then, you could do the following: 700R4 and 3.73. That will help you a lot. Perhaps 3.55 or 2.42 or 3.23. NOW, it sounds like you USE the truck, and that is awesome - so, you may actually need the 4.10 and you may like a manual trans... so, if either is the case, then I think you're stuck with 9 mpg, and that's really ok if you like the truck's perf as is - 9.X is really good for a 4.10 rear 3/4 ton truck I think. While EFI could help - you'd probably have to drive for about 50 yhears to recoup the investment in gas savings. |
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#9 | |
Registered User
Join Date: Oct 2007
Location: Wendell, Idaho
Posts: 608
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Re: Way to improve fuel economy??
Quote:
I like the 4:10's but I am not married to them, I swapped out the front and rear axles because the 12 bolt was a little week for hauling and thats the gearset they came with. I love electronics, just not in my vehicles. I like the simplicity of my truck, I like being able to work on it and I guess EFI kindof scares me. ![]() I guess it sounds like I am shooting down all the ideas I am getting, and that is not my intent. Truth is, I dont know what I am after, I guess it just bugged me that I only went 184 miles and had to fill up again to make it home. Feels like my range is limited. I could have spent all weekend driving in the hills, cutting wood and dinking around, but I had to come back to civilization to get fuel. ![]() Thank you for the suggestions, I appreciate all the good info you guys give. Erik
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1969 4x4 Nothing beats a good rock drill and some dynamite |
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#10 | ||
"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,940
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Re: Way to improve fuel economy??
It's just a fact of life that these rigs were built when gas was way cheaper. We didn't care that rigs got crappy gas mileage back then. A high mileage SBC in a 3/4 ton in the woods is always gonna get crappy gas mileage... period. Even changing the gears and switching to EFI isn't going to be that big of a change. On the highway... sure you'll see a difference. But luggin' a big 3/4 ton 4X4 in the woods is always gonna suck fuel.
Gary
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'cuz chicks dig scars... My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread. The Rebuild of Creeping Death after the wreck Quote:
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#11 |
Registered User
Join Date: Oct 2009
Location: chapel hill north carolina
Posts: 3
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Re: Way to improve fuel economy??
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#12 |
Senior Member
![]() Join Date: Oct 2009
Location: Godley, TX
Posts: 17,963
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Re: Way to improve fuel economy??
aux tank maybe? No worries odog, I do know how ya feel. My 66 gets maybe 11 mpg on a good day (stock 283 in it with a 4 bbl), and I spent a whole summer and more than a few bucks sticking the T5 in it... I shudder to think what my mileage was before.... (i have 3.73s in back)
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#13 | ||
Registered User
Join Date: Oct 2007
Location: Wendell, Idaho
Posts: 608
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Re: Way to improve fuel economy??
Quote:
Quote:
You are right, a heavy truck up and down in the woods isnt good on fuel, just something I need to live with. Thanks guys Erik
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1969 4x4 Nothing beats a good rock drill and some dynamite |
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#14 | ||
"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,940
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Re: Way to improve fuel economy??
Erik... I'm in the same boat... I don't own a single vehicle that gets better than 12 MPG...
![]() Gary
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'cuz chicks dig scars... My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread. The Rebuild of Creeping Death after the wreck Quote:
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#15 |
Registered User
Join Date: Feb 2012
Location: JBLM, WA
Posts: 153
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Re: Way to improve fuel economy??
Nothing worth while. Anything you do will take you years and years to recoup the funds. And THEN you start saving. Make sure its all running 100%, that's all ya can do.
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68 GMC C2500 - 305 V6 - 4spd |
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#16 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
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Re: Way to improve fuel economy??
If it ain't broke,don't fix it. A .4 difference in MPG,especially on such a run,is nil. That could be the difference in atmospheric conditions that day,like barometric pressure/temp. Sounds like you have a good combination. What's all this poo-poo about the 327 not being the right motor,not making enough torque??? Hog wash. It was the biggest engine offered until 1968 and these trucks did everything the world asked them to...probably longer than any other made...and earned a great reputation which lead to the reason all you guys want them 40 years later. They're no just a pretty face. Hauling a load of firewood over hill and dale,back roads mostly in 3rd gear and getting 9+ MPG is doing good.
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"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
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#17 |
Registered User
Join Date: Feb 2011
Location: Modesto, CA
Posts: 2,188
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Re: Way to improve fuel economy??
A well worn SBC pulling a load up and down hills exhaling through a straw can't be good for gas mileage! I would like to think 9 mpgs would be acceptable given all the stats you have given. I know you suggested a big block not being a bad alternative at this point, but a rebuilt mild SBC will always beat out a rebuilt mild BBC for gas mileage. Given a real high mileage BBC with your conditions you could be looking at possibly 7 mpg. That's what the 70s c10 I had was getting before it died out.
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#18 | |
Registered User
Join Date: Apr 2010
Location: Russiaville
Posts: 203
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Re: Way to improve fuel economy??
Quote:
__________________
......its not what your askin', its what your gettin'.... .......every time I screw up, I learn something. Needless to say, I'm learning all the time............ |
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#19 |
Registered User
![]() Join Date: May 2012
Location: Anton, Texas
Posts: 2,364
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Re: Way to improve fuel economy??
odog:get a bigger truck....so you can haul more wood, you wont have to go as often.....lol
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#20 | |
Registered User
Join Date: Oct 2007
Location: Wendell, Idaho
Posts: 608
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Re: Way to improve fuel economy??
Quote:
For now I will just keep on using what I have, shes reliable and I know her issues. I can get 2 cord of wood on her and thats a decent day of cutting.
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1969 4x4 Nothing beats a good rock drill and some dynamite |
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#21 |
Registered User
![]() Join Date: May 2012
Location: Anton, Texas
Posts: 2,364
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Re: Way to improve fuel economy??
dump bed would be nice unloading .....good luck....
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#22 |
Registered User
Join Date: Jun 2009
Location: san francisco, ca (east bay)
Posts: 674
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Re: Way to improve fuel economy??
I have a pickup with a 20 gal tank which I feel like I fill it up every time I get into it.
I have a suburban with a 40 Gallon tank which lasts me a week. It stings a little to put $100 worth of gas in at a time, but I LOVE having the range. Go the bigger tank route, it's likely the cheapest option. I also have a mount for a Jerry can, which is the "no brainer" way to expand your fuel. Though you will easily be into $100 per can mounted. My PO put one of these in the burb: ![]() |
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#23 |
Registered User
![]() Join Date: Nov 2012
Location: Whidbey Island/Edmonds,WA
Posts: 360
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Re: Way to improve fuel economy??
For best mileage, the Rochester is the best carb. Get it rebuilt if it's tired. A big block will make a small difference in mileage, but quite a bit in grunt. An OD trans will help long term, and your gears are right for it, but it won't pay for itself so only do it if you take long trips regularly. Headers will help both mileage and torque, along with the dual exhaust of coarse, but don't expect any miracles.
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If I have to be on 4 wheels, It has to be a classic Chevy 1967 c10 Longbed (Hawghauler/Icy weather transport) 2003 BMW K1200GT (Rain bike) 2007 Softail Deuce (Sun bike) 2009 Ultra Classic Electra Glide (Everything else bike) |
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#24 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
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Re: Way to improve fuel economy??
Yeah,I'd run headers & duals,go head with a GM HEI,nice Q-Jet,big air cleaner,all tuned up
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"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
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#25 |
Registered User
Join Date: Apr 2012
Location: Covington, GA
Posts: 386
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Re: Way to improve fuel economy??
A bit of a tune-up may help, and possibly even some rejetting the carb depending on where your air/fuel ratios are now. Also, do you have a vacuum advance hooked up on the distributor? I've seen those unhooked, and that will hurt mileage significantly.
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Matt Cramer 1972 Chevy C10 - 4.8 swap, long bed, and maybe one dent free body panel somewhere - SOLD 4.8 LS build thread |
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