ITT i track my mpg.....cause it sucks! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

blackbeaSSt · 03-28-2011, 11:13 AM

filled up just now with roughly 14.25 gallons with the odo reading 29704

something just doesn't seem right to only be getting 9-10 out of my q-jet 305.

i'll keep track as i hit the quarter tanks and half tank along with miles driven

tucsonjwt · 03-28-2011, 11:23 AM

In my experience, 9-11 is typical mpg for these old squares in city driving. 13-15 highway mpg is what I would expect - less with towing or heavy loads. A big heavy non-aerodynamic vehicle does not get good gas mileage. A 1/2 ton truck in perfect condition with highway rear axle ratio and careful driving can improve 2-3 mpg. On newer 1/2 ton pickups, I got 19-20 mpg with a 2000 Silverado V6 work truck, and 15.5 mpg with a 2010 Sierra ext cab 4.8L V8 - all city. Like the car ads say: "your mileage will vary."

blackbeaSSt · 03-28-2011, 11:30 AM

i hear ya tucson! i have seen some people with 383's+ getting better around town then mine so i thought i would just track what all im doing and see if someone sees something that im not.

while i can go about 2 weeks on a tank of gas, i only drive it maybe 20 miles or so per day, never bark the tires, rarely get it over 50mph, and do no hauling! maybe i am doomed with 9-10 mpg LOL!

Restrorob · 03-28-2011, 12:05 PM

Best I ever got out my 74 350/350 2bbl is 10 with fresh carb rebuild and FULL tune-up, I figured if it's gonna suck gas I may as well build it a little nasty to make me feel better about it....

71swb4x4 · 03-28-2011, 12:09 PM

tracking 1/4 and 1/2 tanks is really unreliable, it would be best to simply track the gallons and mileage each time you fill up, that will be much more accurate for you.

blackbeaSSt · 03-28-2011, 01:10 PM

Quote:

Originally Posted by 71swb4x4

tracking 1/4 and 1/2 tanks is really unreliable, it would be best to simply track the gallons and mileage each time you fill up, that will be much more accurate for you.

nah i won't be calculating mpg at those times, just updating with miles driven and how long it takes to get there

silvereagle07 · 03-28-2011, 01:38 PM

Wow, I thought they would get better mpg's than that. I get 15-18 with my TBSS 6.0L with 4.10 gears no matter how I drive it. I'll have to check my old swb to see what it's getting.

74chevy4x4 · 03-28-2011, 01:53 PM

My 74 K20 with a SBC350, XE268 Comp Cam, 700R4, and 4.10 gears only gets about 10-12 in town dpending on how heavy my foot is

Most of what I've read is pretty close to that. Of course, if we were looking for great mileage, we wouldn't be driving Old Square Bodies, would we???

75ChevyGuy · 03-28-2011, 02:10 PM

My truck get's around 18 for city. Never take it on the highway. I've got a 350 with a quadrajet and a 3l80. I've got 3:73"s in the rear I believe and 15x8 Rallyes with 295/50's on them. And I'll even gun it from time to time. I was getting about 15MPG before I did a tune up with all ACDelco parts. Maybe all you need is a good tune up?

blackbeaSSt · 03-28-2011, 02:17 PM

Quote:

Originally Posted by 75ChevyGuy

My truck get's around 18 for city. Never take it on the highway. I've got a 350 with a quadrajet and a 3l80. I've got 3:73"s in the rear I believe and 15x8 Rallyes with 295/50's on them. And I'll even gun it from time to time. I was getting about 15MPG before I did a tune up with all ACDelco parts. Maybe all you need is a good tune up?

see this is what throws me for a loop. you got a bigger engine yet you are almost doubling me up on mpg?

what kinda parts did you tune it up with?

Your41Plague12 · 03-28-2011, 03:26 PM

****, I get like 5.5-6 around town and like 7 or 8 on the highway. If I wanted something with better fuel efficiency, I wouldn't be driving something 8 feet tall with the aerodynamics of a brick.

blackbeaSSt · 03-28-2011, 03:45 PM

Quote:

Originally Posted by Your41Plague12

****, I get like 5.5-6 around town and like 7 or 8 on the highway. If I wanted something with better fuel efficiency, I wouldn't be driving something 8 feet tall with the aerodynamics of a brick.

don't get me wrong im not complaining, im mainly trying to get an idea if something is wrong or needs to be replaced

blackbeaSSt · 04-05-2011, 02:31 PM

i hit a half tank this past saturday at mile 29787. so thats 83 miles on a half tank. best case i'll hit 160 on a tank which would be 11mpg. better, but still wondering if something is up

Hulk Will Smash · 04-05-2011, 03:31 PM

I had a '78 Bronco 4x4 with a 400M that got 6mpg. Now I have a crew-dually with a 454 that gets 6mpg. Somehow that makes me feel better.

I too scratch my head when I see a really wild range of MPGs for similar trucks. Maybe best to just add them all up and divide by the number of people who tell you their milage. Heck throw out the highest and lowest internet truck milage and then average the rest? Maybe a good baseline.

dswancutt · 04-05-2011, 05:16 PM

I got 15mpg on the road with calm wind conditions, 11 fighting a 30 to 35 mph headwind this weekend. That is a 78 1/2 ton, 350/350 combo with 3.07 gears and not tuned as good as it should be.

Greenlee · 04-05-2011, 05:19 PM

Back in the day when these trucks were new, I remember hearing the argument that the 350 actually got the same or better mileage than the 305 because the 305 was underpowered for the truck. I never liked the 305 because it seemed like it had no advantages over a 350.

I used to own a single cab 1988 GMC (newer body style) with a TBI 350 and it got great gas mileage. I'm pretty sure it got better gas mileage than the Nissan Titan daily driver that I own now. After the 88' GMC and before the Titan, I had a Nissan Xterra and I remember being really disappointed with the Xterra because I was expecting it to be a fuel miser compared to my truck that was 12 year older. If I remember correctly, my 2000 v6 Xterra and the 88 GMC both got in the neighborhood of 17 mpg.

Srubydo1986 · 04-05-2011, 05:45 PM

back when i had a modern 350 with old school 350 trans i was getting 15-17 mpg believe it or not.

redneckchevy · 04-07-2011, 10:06 PM

My DD is a 86' C-10 with 350/700r4 and i get 12 if i keep my foot out of it, but I avg 9 to 11 MPG. If i take it on a long trip i can get 14-15, the best i have ever got was 16 MPG. Its starting to hurt with the gas prices the way they are tho!

motornut · 04-07-2011, 11:38 PM

If i wana save gas ....I drive my car
If i want comfort or space the truck
I don't count "mpg" I just count how many miles to the next gas station lol

James McClure · 04-08-2011, 08:41 AM

84 K20, 350 eng, 465 trans, 3.08 gears. 15 to 17 mixed driving. 14 to 15 pulling 7000# trailer. I set timing at 14DEG. Will ping if I step down hard though. I rebuilt carb and leaned it out a bit. Choke is set very light. I also drive conservitivly and use every trick in the book to save fuel. Coasting and drafting mostly. jim

Shyguy · 04-08-2011, 08:54 AM

Here is something some people do not make sure is if the speed-o-meter is correct. We have a tendency to put non-stock tire sizes on our trucks which throws off the speed-o-meter and the mpg calcualations.

Neither of my trucks read the correct speed.

Hulk Will Smash · 04-08-2011, 09:35 AM

Calculated 5.37 mpg at my fill up yesterday. Its probably a bit better than that because of the tire diameter difference shyguy mentioned. But, probably not much better. Don't give a crap though, I love my truck!
Posted via Mobile Device

blackbeaSSt · 04-08-2011, 10:03 AM

ok so i didn't even make it to the 160 on a tank mark! hell i only was able to go 131 which comes in a tick over 9mpg

again not that im complaining because i knew going in to buying this truck that it would suck. im just bumfuzzled about the bigger engines getting better mileage. oh well!

jitteryguy · 04-08-2011, 10:27 AM

my '87 Crew cab dually with a 454/TH400 4.11 gears. it was get'n 8.5 in town and bout 10 interstate,
I recently put a CompCam's high energy cam/lifter kit (260 dur./.475 lift) I havent been home to see what it's get'n city now, but I got 13/14 highway when I was on R&R and that was driven it pretty hard . I'm gonna go with a 700R4 and 3.73 gears and be happy with it.
I just stare at my new wheel's while I'm fill'n up so I dont notice how fuel I just bought !

sad thing is I have a '88 S10 (305/700R4) that get's bought 20 city but I still drive the dually more.

rayfinseats · 04-08-2011, 10:51 AM

Try new ac delco parts, cap, rotor, plugs, wires etc and bump your timing up to where it pings under load and then bring it down a few degrees till it stops pinging. Probably about 8bdc at 1000 rpm. We did that on my 90efi and got about abut 1/3 better milage.

03-28-2011, 11:13 AM	#1
blackbeaSSt Registered User Join Date: Sep 2010 Location: Anderson, SC Posts: 325	ITT i track my mpg.....cause it sucks! filled up just now with roughly 14.25 gallons with the odo reading 29704 something just doesn't seem right to only be getting 9-10 out of my q-jet 305. i'll keep track as i hit the quarter tanks and half tank along with miles driven

03-28-2011, 11:23 AM	#2
tucsonjwt Registered User Join Date: Jul 2007 Location: Tucson, AZ Posts: 3,188	Re: ITT i track my mpg.....cause it sucks! In my experience, 9-11 is typical mpg for these old squares in city driving. 13-15 highway mpg is what I would expect - less with towing or heavy loads. A big heavy non-aerodynamic vehicle does not get good gas mileage. A 1/2 ton truck in perfect condition with highway rear axle ratio and careful driving can improve 2-3 mpg. On newer 1/2 ton pickups, I got 19-20 mpg with a 2000 Silverado V6 work truck, and 15.5 mpg with a 2010 Sierra ext cab 4.8L V8 - all city. Like the car ads say: "your mileage will vary."

03-28-2011, 11:30 AM	#3
blackbeaSSt Registered User Join Date: Sep 2010 Location: Anderson, SC Posts: 325	Re: ITT i track my mpg.....cause it sucks! i hear ya tucson! i have seen some people with 383's+ getting better around town then mine so i thought i would just track what all im doing and see if someone sees something that im not. while i can go about 2 weeks on a tank of gas, i only drive it maybe 20 miles or so per day, never bark the tires, rarely get it over 50mph, and do no hauling! maybe i am doomed with 9-10 mpg LOL!

03-28-2011, 12:05 PM	#4
Restrorob The One And Only !!! Join Date: Jan 2007 Location: Hole in the woods Florida Posts: 4,567	Re: ITT i track my mpg.....cause it sucks! Best I ever got out my 74 350/350 2bbl is 10 with fresh carb rebuild and FULL tune-up, I figured if it's gonna suck gas I may as well build it a little nasty to make me feel better about it.... __________________ 93 Jeep XJ 88 Buick La Sabra Toys; 88 TA-GTA in the works.... 97 GMC Ext. Cab 502 Crate 5 Spd......Sucks Gas But Haulz Azz ! The primary function of an Engineer is to make it difficult for the Fabricator and impossible for the Mechanic. *"Why go out preserved when you can go out beat up, worn out, sliding in sideways screaming, Holy Sh!t What A Ride" !!!*

03-28-2011, 12:09 PM	#5
71swb4x4 Senior Member Join Date: Nov 2003 Location: Brookings, SD Posts: 10,497	Re: ITT i track my mpg.....cause it sucks! tracking 1/4 and 1/2 tanks is really unreliable, it would be best to simply track the gallons and mileage each time you fill up, that will be much more accurate for you. __________________ Some people are like slinkies, they aren't good for anything, but you can't help but smile when you see one tumble down the stairs.

03-28-2011, 01:38 PM	#7
silvereagle07 Registered User Join Date: Sep 2008 Location: Bailey, NC Posts: 2,462	Re: ITT i track my mpg.....cause it sucks! Wow, I thought they would get better mpg's than that. I get 15-18 with my TBSS 6.0L with 4.10 gears no matter how I drive it. I'll have to check my old swb to see what it's getting. __________________ Jeramy '84 GMC project truck '85 Chevy 4X4 SOLD '07 Chevy Trailblazer SS 5th Annual SHPHC Car/Truck Show Pics http://67-72chevytrucks.com/vboard/s...d.php?t=543605 UPDATED PICS! CHECK 'EM OUT

03-28-2011, 01:53 PM	#8
74chevy4x4 Registered User Join Date: Aug 2010 Location: Clarksville, TN Posts: 28	Re: ITT i track my mpg.....cause it sucks! My 74 K20 with a SBC350, XE268 Comp Cam, 700R4, and 4.10 gears only gets about 10-12 in town dpending on how heavy my foot is Most of what I've read is pretty close to that. Of course, if we were looking for great mileage, we wouldn't be driving Old Square Bodies, would we??? __________________ 1974 K20 Cheyenne Super, 350ci with Edelbrock Valve Covers, Intake and Carb, COMP CAMs XE268h, Headers from Jeggs, 65K Volt HEI Distributor, Mile Marker Locking Hubs, 700R4 Tranny, NP241C Transfer, A/C, tilt wheel, dual 20 Gal tanks. 2003 Honda VTX-1800C, V&H Big Shots, Kury Hypercharger, grips, pegs, Darkside Goodyear Triple Tread Rear Tire, and Chrome Galor. 2005 Chevy Trailblazer(Momma's Car LoL)

03-28-2011, 02:10 PM	#9
75ChevyGuy GM Parts Guy Join Date: Jan 2011 Location: Attleboro MA Posts: 375	Re: ITT i track my mpg.....cause it sucks! My truck get's around 18 for city. Never take it on the highway. I've got a 350 with a quadrajet and a 3l80. I've got 3:73"s in the rear I believe and 15x8 Rallyes with 295/50's on them. And I'll even gun it from time to time. I was getting about 15MPG before I did a tune up with all ACDelco parts. Maybe all you need is a good tune up? __________________ 1975 Chevrolet C-10 Custom Deluxe (DD/WIP) 1989 Chevrolet C1500 reg cab stepside (Winter Truck) 1977 Harley Davidson XLH 1000 (Summer Cruiser)

03-28-2011, 03:26 PM	#11
Your41Plague12 Registered User Join Date: Dec 2010 Location: Pittsburgh, PA Posts: 1,009	Re: ITT i track my mpg.....cause it sucks! ****, I get like 5.5-6 around town and like 7 or 8 on the highway. If I wanted something with better fuel efficiency, I wouldn't be driving something 8 feet tall with the aerodynamics of a brick. __________________ Steve Member of the Foot Pedal Club '83 Chevy K20: 6" Rough Country, 3" Performance Accessories BL, Bushwacker Cutouts, 38x15.50 Mickey Thompson Baja Claws, 350 HP 350 crate engine from Jegs, Turbo 400

04-05-2011, 02:31 PM	#13
blackbeaSSt Registered User Join Date: Sep 2010 Location: Anderson, SC Posts: 325	Re: ITT i track my mpg.....cause it sucks! i hit a half tank this past saturday at mile 29787. so thats 83 miles on a half tank. best case i'll hit 160 on a tank which would be 11mpg. better, but still wondering if something is up

04-05-2011, 03:31 PM	#14
Hulk Will Smash Registered User Join Date: Apr 2006 Location: Huntington Beach, CA Posts: 492	Re: ITT i track my mpg.....cause it sucks! I had a '78 Bronco 4x4 with a 400M that got 6mpg. Now I have a crew-dually with a 454 that gets 6mpg. Somehow that makes me feel better. I too scratch my head when I see a really wild range of MPGs for similar trucks. Maybe best to just add them all up and divide by the number of people who tell you their milage. Heck throw out the highest and lowest internet truck milage and then average the rest? Maybe a good baseline. __________________ '87 R30 Crew Cab Dually It's 11 PM, do you know where your IAC pintle is?

04-05-2011, 05:16 PM	#15
dswancutt Registered User Join Date: Jul 2003 Location: Franklin, NE Posts: 387	Re: ITT i track my mpg.....cause it sucks! I got 15mpg on the road with calm wind conditions, 11 fighting a 30 to 35 mph headwind this weekend. That is a 78 1/2 ton, 350/350 combo with 3.07 gears and not tuned as good as it should be.

04-05-2011, 05:19 PM	#16
Greenlee Registered User Join Date: Jun 2004 Location: El Lago, TX Posts: 1,668	Re: ITT i track my mpg.....cause it sucks! Back in the day when these trucks were new, I remember hearing the argument that the 350 actually got the same or better mileage than the 305 because the 305 was underpowered for the truck. I never liked the 305 because it seemed like it had no advantages over a 350. I used to own a single cab 1988 GMC (newer body style) with a TBI 350 and it got great gas mileage. I'm pretty sure it got better gas mileage than the Nissan Titan daily driver that I own now. After the 88' GMC and before the Titan, I had a Nissan Xterra and I remember being really disappointed with the Xterra because I was expecting it to be a fuel miser compared to my truck that was 12 year older. If I remember correctly, my 2000 v6 Xterra and the 88 GMC both got in the neighborhood of 17 mpg.

04-05-2011, 05:45 PM	#17
Srubydo1986 The Crazy Machanic Join Date: Jan 2007 Location: Nokesville Va Posts: 1,437	Re: ITT i track my mpg.....cause it sucks! back when i had a modern 350 with old school 350 trans i was getting 15-17 mpg believe it or not. __________________ 1986 Sliverado longbed 400 small block mean as hell, 700r4 trans (5 speed coming one day) 1970 chevelle 2dr sedan Latest update June 24 2007. *1957 4 door stationwagon - pink all original needing a good restore (body great, floors bad) newest additions 1965 shortbed fleet great granddads. Been told im nuts to bring it back from the dead (still going to happen) plans-all stock with a turbo 292 inline 3 speed column shift. and thats it big block 427 and 5 speed trans and ford 9 inch theyhave no home yet thinking what to put them in and a 79 c60 trash truck um no idea i have one

04-07-2011, 10:06 PM	#18
redneckchevy Registered User Join Date: Feb 2010 Location: Tony, WI Posts: 69	Re: ITT i track my mpg.....cause it sucks! My DD is a 86' C-10 with 350/700r4 and i get 12 if i keep my foot out of it, but I avg 9 to 11 MPG. If i take it on a long trip i can get 14-15, the best i have ever got was 16 MPG. Its starting to hurt with the gas prices the way they are tho!



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04-07-2011, 11:38 PM	#19
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: ITT i track my mpg.....cause it sucks! If i wana save gas ....I drive my car If i want comfort or space the truck I don't count "mpg" I just count how many miles to the next gas station lol __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350

04-08-2011, 08:41 AM	#20
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: ITT i track my mpg.....cause it sucks! 84 K20, 350 eng, 465 trans, 3.08 gears. 15 to 17 mixed driving. 14 to 15 pulling 7000# trailer. I set timing at 14DEG. Will ping if I step down hard though. I rebuilt carb and leaned it out a bit. Choke is set very light. I also drive conservitivly and use every trick in the book to save fuel. Coasting and drafting mostly. jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

04-08-2011, 08:54 AM	#21
Shyguy Junior Member Join Date: Dec 2006 Location: Southeast Missouri Posts: 2,436	Re: ITT i track my mpg.....cause it sucks! Here is something some people do not make sure is if the speed-o-meter is correct. We have a tendency to put non-stock tire sizes on our trucks which throws off the speed-o-meter and the mpg calcualations. Neither of my trucks read the correct speed. __________________ '67 Chevy C-20 short stepper - build complete, 454/SM-465. '75 C-30 Single Cab DRW-350 small block/NP-435. '77 GMC-6500 Dump Truck, 427 Tall Deck. '92 GMC K-3500 Duallie, 454/4L80E.

04-08-2011, 09:35 AM	#22
Hulk Will Smash Registered User Join Date: Apr 2006 Location: Huntington Beach, CA Posts: 492	Re: ITT i track my mpg.....cause it sucks! Calculated 5.37 mpg at my fill up yesterday. Its probably a bit better than that because of the tire diameter difference shyguy mentioned. But, probably not much better. Don't give a crap though, I love my truck! Posted via Mobile Device __________________ '87 R30 Crew Cab Dually It's 11 PM, do you know where your IAC pintle is?

04-08-2011, 10:03 AM	#23
blackbeaSSt Registered User Join Date: Sep 2010 Location: Anderson, SC Posts: 325	Re: ITT i track my mpg.....cause it sucks! ok so i didn't even make it to the 160 on a tank mark! hell i only was able to go 131 which comes in a tick over 9mpg again not that im complaining because i knew going in to buying this truck that it would suck. im just bumfuzzled about the bigger engines getting better mileage. oh well!

04-08-2011, 10:27 AM	#24
jitteryguy GoatLube Experss Join Date: Oct 2009 Location: clarksville, Tn. Posts: 1,337	Re: ITT i track my mpg.....cause it sucks! my '87 Crew cab dually with a 454/TH400 4.11 gears. it was get'n 8.5 in town and bout 10 interstate, I recently put a CompCam's high energy cam/lifter kit (260 dur./.475 lift) I havent been home to see what it's get'n city now, but I got 13/14 highway when I was on R&R and that was driven it pretty hard . I'm gonna go with a 700R4 and 3.73 gears and be happy with it. I just stare at my new wheel's while I'm fill'n up so I dont notice how fuel I just bought ! sad thing is I have a '88 S10 (305/700R4) that get's bought 20 city but I still drive the dually more. __________________ *Goat Lube Express*, locations in Qalat,Afghanistan & Clarksville, Tn. '87 R30 dually 454/TH400 '85 1/2 ton CCSB '92 S10 350/350 '84 MonteCarlo 383/PG/9"ford '78 Malibu wagon 350/350 '78 Cutlass (project family car) '96 S10 Jimmy (Moma's)

04-08-2011, 10:51 AM	#25
rayfinseats Registered User Join Date: Dec 2010 Location: sioux city, iowa Posts: 619	Re: ITT i track my mpg.....cause it sucks! Try new ac delco parts, cap, rotor, plugs, wires etc and bump your timing up to where it pings under load and then bring it down a few degrees till it stops pinging. Probably about 8bdc at 1000 rpm. We did that on my 90efi and got about abut 1/3 better milage.

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