Why do I burn so much fuel??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

70c10 · 08-22-2004, 10:30 PM

I don't have any fuel leaks but my truck has always used gas like no tomorrow!. I only get 6 or 7mpg with my small block. It runs great but what gives???. Any thoughts???.

jhow66 · 08-22-2004, 10:40 PM

Heavy foot??

70c10 · 08-22-2004, 10:41 PM

Absolutely!

, all the time, but still I didn't think it should eat that much gas.

Longhorn Man · 08-22-2004, 11:02 PM

Baby it for a week and see what it'll do.
What kind of MPG you get on the open road?

Leinie · 08-22-2004, 11:13 PM

I'll agree that it's your lead foot. My 72 Blazer ( Stock) got about 8 mpg until I started taking it easy on the gas pedal. Got over 10 mpg regularly after deciding to drive better

70c10 · 08-22-2004, 11:23 PM

I'll take it easy for awhile to test it. On the highway today I got 6 or 7 while nailing it a few times.

Bill72BB · 08-23-2004, 12:26 AM

Quote:

Originally Posted by 70c10

I'll take it easy for awhile to test it. On the highway today I got 6 or 7 while nailing it a few times.

If you are still running the Q-Jet keep in mind it is designed to dump a massive amount of gas when the secondary 's kick in .

71-longbed · 08-23-2004, 01:22 AM

is your speedometer accurate ???

1BadSS · 08-23-2004, 04:25 AM

Quote:

Originally Posted by 70c10

I don't have any fuel leaks but my truck has always used gas like no tomorrow!. I only get 6 or 7mpg with my small block. It runs great but what gives???. Any thoughts???.

Our trucks weren't the most aerodynamic beasts on the market, do you have a open bed and a tailgate on your truck? Thats one thing to add to bad mileage. Heck, I can watch my fuel injected 4.3liter 98 blazer guzzle gas like no tomorrow, try keeping the truck under 55, if you're all that concerned with gas mileage.

70c10 · 08-23-2004, 07:13 AM

Bill- I'm running a Demon carb right now.

71longbed- My speedometer is about 10 miles per hour high.

Josh- your right about the aerodynamics of these trucks but still 6 or 7 mpg is big block gas mileage!. I'm not overly concerned about mileage but it would be nice to be at least 10. Your also right about the Blazer, I just picked up a 98' 3 weeks ago and it gets 10mpg!

1BadSS · 08-23-2004, 07:22 AM

Quote:

Originally Posted by 70c10

Bill- I'm running a Demon carb right now.

71longbed- My speedometer is about 10 miles per hour high.

Josh- your right about the aerodynamics of these trucks but still 6 or 7 mpg is big block gas mileage!. I'm not overly concerned about mileage but it would be nice to be at least 10. Your also right about the Blazer, I just picked up a 98' 3 weeks ago and it gets 10mpg!

Try keeping the blazer under 55, and it'll barely sip the gas. Those 4.3 vortec's are quite torquey motors for what they are. I'm always joking around about how my 68 impala with a built 350 got over 20+mpg and I ran the ever loving piss out of it daily. I can baby the blazer and hope to get 10mpg.

bigjimzlll · 08-23-2004, 08:01 AM

6-7MPG and your complaining???? Take my truck for a spin...lol... I use 12 Gallons to go 20 miles and make 4 passes on the 1/4 mile...and thats at 4.00 a gallon fuel..LOL

70c10 · 08-23-2004, 09:30 AM

You gotta good point Jim!. Lets swap motors

just for one ride!. That thing must be a blast to drive!

1BadSS · 08-23-2004, 09:31 AM

Quote:

Originally Posted by 70c10

You gotta good point Jim!. Lets swap motors

just for one ride!. That thing must be a blast to drive!

or you could just pickup my 69... I'm sure with those 1.72"/1.5" valves it'll be a baby with the gas.

Stryker67 · 08-23-2004, 01:57 PM

Cause you can......duh.

franko72 · 08-24-2004, 05:28 PM

They sure are thirsty beasts .my big block gets about 10 mpg when I drive sensible, when I hammer it I am afraid to check what I am getting , maybe 5 or 6 mpg I guess.

rust!!whatrust? · 03-01-2007, 01:54 AM

Consider your gearing. Also consider your trans.

brak · 03-01-2007, 02:46 AM

Quote:

Originally Posted by 1BadSS

... do you have a open bed and a tailgate on your truck? Thats one thing to add to bad mileage...

That's a myth, you actually hurt the aerodynamics if you install a tonneau, or remove the tailgate.

the open bed creates a swirling effect that forces most of the air up and over the bed, wheras, without the tailgate, or with a tonneau, that swirling effect is eliminated, causing the air to come over the cab and directly down on the rear causing drag.

Here's a quick illustration, just remember, nobody's ever accused me of being an artist

I believe mythbusters may have done an episode on this a few years ago using a wind tunnel.

stsalvage · 03-01-2007, 04:42 AM

well i got one even better you Know why simi trucks don't run low profile tires cus there trying the get the milage out of the high tires . On my 1965 3/4 ton chevy i have a tired 350 with over 390,000 miles on it with a little blow by with a power glide with 411 rear gears No i was getting 9 miles per gallon i went to a eldalbrook 4 bb carb and i'm running 235/85/16 went from 9 miles to 14 miles and i run about 9 miles faster on my speedo but i can tell the diffrence and i did this as well

I Ajust the passing gear Rod so that the secont daires would not open unless i really steped on it and not all the time the secont daries would open and from what i'm hearing Gas is going back to $3.00 a gallon soon

cableguy0 · 03-01-2007, 07:16 AM

what rpm do you normally run at on the highway? if your above 3000 its going to drink the fuel. try to keep it under 3000rpm the next time you drive it and see what happens.is that carb mechanical or vac secondaries? i dont remember. it could possibly have too light of a spring if it vac advance and opening the secondaries a bit under cruise

cdowns · 03-01-2007, 07:32 AM

these trucks were designed and built when gas was 3gallons for a dollar//add a cam subtract mileage,a performance carb subtract mileage,poor driving skills subtract mileage,oversize wheels and tires subtract mileage//to get good mileage on these trucks a consious effort must be made in the total package suspension engine package tranny and rear gearing even then its an effort to have a somewhat performance package and get over 16or so mpg

70c10 · 03-01-2007, 07:42 AM

Wow- I started this thread back in 2004 and somebody is digging it up?

I gave up on the fuel mileage a long time ago since it's just a cruiser

cableguy0 · 03-01-2007, 07:51 AM

i didnt even look at the date of original post wow people gotta stop doing this

70c10 · 03-01-2007, 08:23 AM

Quote:

Originally Posted by cableguy0

i didnt even look at the date of original post wow people gotta stop doing this

Longhorn Man · 03-01-2007, 11:27 AM

new guys bringing up 7 month old dead posts.
However, look at this thread... http://67-72chevytrucks.com/vboard/s...d.php?t=172346
Almost 1/2 the ppl here on this board, claim they get 10 to 12 MPG.

08-22-2004, 10:30 PM	#1
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Why do I burn so much fuel??? I don't have any fuel leaks but my truck has always used gas like no tomorrow!. I only get 6 or 7mpg with my small block. It runs great but what gives???. Any thoughts???. __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

08-22-2004, 10:40 PM	#2
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Heavy foot?? __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

08-22-2004, 10:41 PM	#3
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Absolutely! , all the time, but still I didn't think it should eat that much gas. __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

08-22-2004, 11:23 PM	#6
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	I'll take it easy for awhile to test it. On the highway today I got 6 or 7 while nailing it a few times. __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

08-23-2004, 01:22 AM	#8
71-longbed Its Magically Delicious Join Date: Jan 2003 Location: oregon Posts: 2,398	is your speedometer accurate ??? __________________ 71 C10 LWB 350sbc -TH350 12 bolt 3.42 Posi Of all my favorite things to do, The utmost is to have a brew. My love grows for my foamy friend, with each thirst-quenching elbow bend. Beer so frosty, smooth, and cold it's paradise pure liquid gold. Yes beer means many things to me that's all for now cus I gotta pee.

08-22-2004, 11:02 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Baby it for a week and see what it'll do. What kind of MPG you get on the open road?

08-22-2004, 11:13 PM	#5
Leinie Registered User Join Date: Feb 2001 Location: USA Posts: 2,613	I'll agree that it's your lead foot. My 72 Blazer ( Stock) got about 8 mpg until I started taking it easy on the gas pedal. Got over 10 mpg regularly after deciding to drive better

08-23-2004, 07:13 AM	#10
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Bill- I'm running a Demon carb right now. 71longbed- My speedometer is about 10 miles per hour high. Josh- your right about the aerodynamics of these trucks but still 6 or 7 mpg is big block gas mileage!. I'm not overly concerned about mileage but it would be nice to be at least 10. Your also right about the Blazer, I just picked up a 98' 3 weeks ago and it gets 10mpg! __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

08-23-2004, 08:01 AM	#12
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	6-7MPG and your complaining???? Take my truck for a spin...lol... I use 12 Gallons to go 20 miles and make 4 passes on the 1/4 mile...and thats at 4.00 a gallon fuel..LOL __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA

08-23-2004, 09:30 AM	#13
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	You gotta good point Jim!. Lets swap motors just for one ride!. That thing must be a blast to drive! __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

08-23-2004, 01:57 PM	#15
Stryker67 Registered User Join Date: May 2004 Location: Fayetteville, Ga. Posts: 150	Cause you can......duh. __________________ [FONT=Georgia] If nothing else, we can all serve as a bad example. We don't know what we don't know. The world needs ditch-diggers too.

08-24-2004, 05:28 PM	#16
franko72 Franko72 Join Date: May 2004 Location: Cincinnati,Ohio Posts: 471	They sure are thirsty beasts .my big block gets about 10 mpg when I drive sensible, when I hammer it I am afraid to check what I am getting , maybe 5 or 6 mpg I guess. __________________ 1972 C20 cheyenne Super 402 BB/400 turbo LWB A/C Tilt, Cruise Control, Saddle tanks, Tach My Home Page Better to burn out than it is to rust

03-01-2007, 01:54 AM	#17
rust!!whatrust? Registered User Join Date: Mar 2006 Location: chattanooga tn. Posts: 27	Re: Why do I burn so much fuel??? Consider your gearing. Also consider your trans. __________________ Don't touch the Rust. Punk

03-01-2007, 04:42 AM	#19
stsalvage Scrapper 1 Join Date: Jan 2007 Location: Riverside Calif Posts: 1,649	Re: Why do I burn so much fuel??? well i got one even better you Know why simi trucks don't run low profile tires cus there trying the get the milage out of the high tires . On my 1965 3/4 ton chevy i have a tired 350 with over 390,000 miles on it with a little blow by with a power glide with 411 rear gears No i was getting 9 miles per gallon i went to a eldalbrook 4 bb carb and i'm running 235/85/16 went from 9 miles to 14 miles and i run about 9 miles faster on my speedo but i can tell the diffrence and i did this as well I Ajust the passing gear Rod so that the secont daires would not open unless i really steped on it and not all the time the secont daries would open and from what i'm hearing Gas is going back to $3.00 a gallon soon

03-01-2007, 07:16 AM	#20
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	Re: Why do I burn so much fuel??? what rpm do you normally run at on the highway? if your above 3000 its going to drink the fuel. try to keep it under 3000rpm the next time you drive it and see what happens.is that carb mechanical or vac secondaries? i dont remember. it could possibly have too light of a spring if it vac advance and opening the secondaries a bit under cruise __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.



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03-01-2007, 07:32 AM	#21
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Why do I burn so much fuel??? these trucks were designed and built when gas was 3gallons for a dollar//add a cam subtract mileage,a performance carb subtract mileage,poor driving skills subtract mileage,oversize wheels and tires subtract mileage//to get good mileage on these trucks a consious effort must be made in the total package suspension engine package tranny and rear gearing even then its an effort to have a somewhat performance package and get over 16or so mpg __________________ 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

03-01-2007, 07:42 AM	#22
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Re: Why do I burn so much fuel??? Wow- I started this thread back in 2004 and somebody is digging it up? I gave up on the fuel mileage a long time ago since it's just a cruiser __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

03-01-2007, 07:51 AM	#23
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	Re: Why do I burn so much fuel??? i didnt even look at the date of original post wow people gotta stop doing this __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

03-01-2007, 11:27 AM	#25
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: Why do I burn so much fuel??? new guys bringing up 7 month old dead posts. However, look at this thread... http://67-72chevytrucks.com/vboard/s...d.php?t=172346 Almost 1/2 the ppl here on this board, claim they get 10 to 12 MPG.

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