Big Block Guys.......Average MPG Questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TP from Cntl PA · 01-22-2006, 09:14 PM

I am looking at a truck with a Big Block(K20) and was wondering what you guys that are running them average fuel mileage wise. I always wanted a K20, not to mention it will allow me to have a truck while I do all the body work to my C20 Cummins truck. This truck has had a 454 installed running through a 4 spd.

Also, anyone running an NV4500, NV5600, or 6spd ZF behind a big block?

JAKES 68GMC · 01-22-2006, 10:20 PM

Don't know mileage, but glad to see that you may be getting a 4x4.

TP from Cntl PA · 01-22-2006, 10:27 PM

Quote:

Originally Posted by JAKES 68GMC

Don't know mileage, but glad to see that you may be getting a 4x4.

Yup, this one may cost me, but buddy is it setup 90% how I'd want it. 4 spd, 4x4, both reciever and gooseneck hitch, brake controller, CB, stakebody, headache rack, tool boxes underneith, west coast mirrors, etc. Not really crazy about the 454(Yet), I'd have rather had a 292 for what I am doing, but what the heck

If I get it I'll pop a 5 or 6 spd behind it and see what she can do.

Just concerned with mpg, because I'll have to drive it daily until my Cummins powered truck is finished 100%.

Longhorn Man · 01-22-2006, 10:32 PM

I 'think' I get about 9 - 11 MPG.
I've only checked a few times, and that's what it was at.
Caddy 500 w/edelbrock 750 TH350 and 4.10 gears.

TP from Cntl PA · 01-22-2006, 10:34 PM

Quote:

Originally Posted by Longhorn Man

I 'think' I get about 9 - 11 MPG.
I've only checked a few times, and that's what it was at.
Caddy 500 w/edelbrock 750 TH350 and 4.10 gears.

I could live with that when you consider I could pull most mountains here in high gear.................That is worth the extra fuel

junior219 · 01-22-2006, 11:31 PM

hahahaha, It's a big block baby. WHO CARES. you the gas and it goes, mmmmmmm POWER

BowTieMan · 01-22-2006, 11:35 PM

This weekend I was at a local car meet with a board member and his friend said he needed a big block in his 59. But he said it would be a daily driver so gas would suck and his friend looked at him serious and said "ya......but you will have a big block"

If you want power and some gas go with a small block.

If you want power and even more power go with the big block.

KFreddy · 01-22-2006, 11:48 PM

I have a '72 with a 454ci, TH400, and 3.08 gears, City is 6-9, Highway 8-14, keeping in mind I'm on the loud pedal quite often...

Livrat · 01-23-2006, 12:37 AM

My 68 - 3/4 ton 4X4 weighing in at #5890 lbs,with 468 ,T350 trans, 3:73 gears and 35 inch tall rubber gets between 8 - 12 mpg depending on the loud pedal.

My 71 - 1/2 ton Suburban with a stock 454, T350 trans, 3:73 gears gets 11 - 14 mpg

My 71 2WD Blazer with a built 454 and close ratio Muncie 4sp. 3:73 gears and short tires gets 8 - 10 mpg .. if you drive it tenderly.. which is hard too do!!

Big blocks.... the only way!!.. the only substitute is a Bigger Big Block

409biscayne · 01-23-2006, 12:54 AM

My 396 bb only uses 3-4 gallons a week . Of c12 race gas at the drag strip

You'll love the big block power , the gas you'll learn to live with . For what it's worth my 96 3500 w/ vortec 454 got a consistent 14 mpg , i thought that was pretty decent . Good luck with the k20.

72 CustomCamper · 01-23-2006, 01:11 AM

My 72 C/20 has a 396 with a 850 cfm Q-jet 700r4 combo with 4:10 rear and I'm lucky to get 5 mpg...

Chuck

Frizzle Fry · 01-23-2006, 02:01 AM

8 city in a 396/400/3.73 Burb. That's with a POS Torquer II manifold and a leaky Holley... Not enough highway miles with that setup to average.

dwaite72lnghrn · 01-23-2006, 07:25 AM

I got about 10mpg short trips, 12.5mpg highway 402/qjet/th400/4.11. Same combo except 1411 edelbrock 10mpg short 10.5mpg highway. Now a ht502/1411/th400/4.11 10mpg short 11mpg highway. Towing 5000lb-6000lb it drops to 8mpg. Really thinking of going back to the Qjet.

vtblazer · 01-23-2006, 08:34 AM

Not really so different than my other trucks with a small block believe it or not...

K-20/396/th-350/4:11's/285-16 tires

Although the over drive I just installed did change that for the better.

Driving around town is the better fuel saving's cause pushing it down the interstate @ 75mph is getting into the pedal more just due to our trucks superior aerodynamics.

72MARIO · 01-23-2006, 10:07 AM

Thoes better MPG than my 355 in my 84. Where can I find a big block mabye I can gain a MPG or two ?

01-22-2006, 09:14 PM	#1
TP from Cntl PA Registered User Join Date: Apr 2003 Location: Central PA....In the Berg of Nisbet Posts: 790	Big Block Guys.......Average MPG Questions I am looking at a truck with a Big Block(K20) and was wondering what you guys that are running them average fuel mileage wise. I always wanted a K20, not to mention it will allow me to have a truck while I do all the body work to my C20 Cummins truck. This truck has had a 454 installed running through a 4 spd. Also, anyone running an NV4500, NV5600, or 6spd ZF behind a big block? __________________ '72 K-20 EFI'ed 250 Inline/4spd stake body, Farm Truck '71 C-20 Cummins Diesel Powered, In storage thanks to $5.00 diesel! '69 3500 GMC 305V-6/4spd, Still under reconstruction.......... Inlines Rule! 6 soldiers standing is better than 8 laying down!!!!!!!!

01-22-2006, 10:20 PM	#2
JAKES 68GMC Aluminum slot wheels rule... Join Date: Jan 2006 Location: Maine Posts: 6,211	Re: Big Block Guys.......Average MPG Questions Don't know mileage, but glad to see that you may be getting a 4x4.

01-22-2006, 10:32 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: Big Block Guys.......Average MPG Questions I 'think' I get about 9 - 11 MPG. I've only checked a few times, and that's what it was at. Caddy 500 w/edelbrock 750 TH350 and 4.10 gears.

01-22-2006, 11:31 PM	#6
junior219 Registered User Join Date: Jul 2005 Location: delta,canada Posts: 19	Re: Big Block Guys.......Average MPG Questions hahahaha, It's a big block baby. WHO CARES. you the gas and it goes, mmmmmmm POWER

01-22-2006, 11:35 PM	#7
BowTieMan Registered User Join Date: Dec 2003 Location: Glendale Arizona Posts: 747	Re: Big Block Guys.......Average MPG Questions This weekend I was at a local car meet with a board member and his friend said he needed a big block in his 59. But he said it would be a daily driver so gas would suck and his friend looked at him serious and said "ya......but you will have a big block" If you want power and some gas go with a small block. If you want power and even more power go with the big block. __________________ "A true hotrodder wouldn't be content untill he had created a car so violent, so hairy, so totally sick that the very act of dropping the hammer would result in instant death. Anything less results in the need to go faster." - Tony DeFeo

01-22-2006, 11:48 PM	#8
KFreddy Active Member Join Date: Apr 2005 Location: Miami, Florida Posts: 286	Re: Big Block Guys.......Average MPG Questions I have a '72 with a 454ci, TH400, and 3.08 gears, City is 6-9, Highway 8-14, keeping in mind I'm on the loud pedal quite often...

01-23-2006, 12:37 AM	#9
Livrat Member #1049 Join Date: Jun 2000 Location: Troy Montana Posts: 3,940	Re: Big Block Guys.......Average MPG Questions My 68 - 3/4 ton 4X4 weighing in at #5890 lbs,with 468 ,T350 trans, 3:73 gears and 35 inch tall rubber gets between 8 - 12 mpg depending on the loud pedal. My 71 - 1/2 ton Suburban with a stock 454, T350 trans, 3:73 gears gets 11 - 14 mpg My 71 2WD Blazer with a built 454 and close ratio Muncie 4sp. 3:73 gears and short tires gets 8 - 10 mpg .. if you drive it tenderly.. which is hard too do!! Big blocks.... the only way!!.. the only substitute is a Bigger Big Block

01-23-2006, 12:54 AM	#10
409biscayne Senior Member Join Date: Nov 2005 Location: Spokane , Wash. Posts: 790	Re: Big Block Guys.......Average MPG Questions My 396 bb only uses 3-4 gallons a week . Of c12 race gas at the drag strip You'll love the big block power , the gas you'll learn to live with . For what it's worth my 96 3500 w/ vortec 454 got a consistent 14 mpg , i thought that was pretty decent . Good luck with the k20. __________________ Can-Am Motorsports 37 Chev Coupe 331 4 speed 5.13 posi . ex-gasser . 64 Biscayne 409 2x4 4 speed 4.11 posi 65 Nova Wagon Drag Car 383 t400 (Dragin-Wagon) 68 c10 cst 396 t400 a/c buckets lwb 4.11 posi (SOLD)

01-23-2006, 01:11 AM	#11
72 CustomCamper huh ??? Join Date: Nov 2002 Location: Fredericksburg,Va. Posts: 3,368	Re: Big Block Guys.......Average MPG Questions My 72 C/20 has a 396 with a 850 cfm Q-jet 700r4 combo with 4:10 rear and I'm lucky to get 5 mpg... Chuck __________________ 90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!" Last edited by 72 CustomCamper; 01-23-2006 at 01:12 AM.

01-23-2006, 02:01 AM	#12
Frizzle Fry Registered User Join Date: Aug 2005 Location: Hillsboro Oregon Posts: 6,449	Re: Big Block Guys.......Average MPG Questions 8 city in a 396/400/3.73 Burb. That's with a POS Torquer II manifold and a leaky Holley... Not enough highway miles with that setup to average.

01-23-2006, 07:25 AM	#13
dwaite72lnghrn Registered User Join Date: Jun 2002 Location: central pa Posts: 1,525	Re: Big Block Guys.......Average MPG Questions I got about 10mpg short trips, 12.5mpg highway 402/qjet/th400/4.11. Same combo except 1411 edelbrock 10mpg short 10.5mpg highway. Now a ht502/1411/th400/4.11 10mpg short 11mpg highway. Towing 5000lb-6000lb it drops to 8mpg. Really thinking of going back to the Qjet. __________________ 72 longhorn c30 502BB/th400/fact air/4.11rear/ custom camper 72 bug(the better half's) under reconstruction 2009 HHR aqua blue 71 GMC k20 350/sm465 2009 Chevy hd3500 6.6 Victory Red crew cab dually Dave & Jeanne

01-23-2006, 08:34 AM	#14
vtblazer Registered User Join Date: Oct 2003 Location: Central Vermont Posts: 8,537	Re: Big Block Guys.......Average MPG Questions Not really so different than my other trucks with a small block believe it or not... K-20/396/th-350/4:11's/285-16 tires Although the over drive I just installed did change that for the better. Driving around town is the better fuel saving's cause pushing it down the interstate @ 75mph is getting into the pedal more just due to our trucks superior aerodynamics. Last edited by vtblazer; 01-23-2006 at 08:34 AM.

01-23-2006, 10:07 AM	#15
72MARIO Registered User Join Date: Nov 2000 Location: Huntsville Ontario Canada Posts: 4,051	Re: Big Block Guys.......Average MPG Questions Thoes better MPG than my 355 in my 84. Where can I find a big block mabye I can gain a MPG or two ? __________________ 1968 Suburban numbers matching all original truck now equipped with 6.0/4L80 on Accuair http://67-72chevytrucks.com/vboard/s...d.php?t=625017 1967 C/20 6.0/4L80 Roofing Truck 1990 V2500 Suburban "Plow Truck" 2005 TAHOE DD

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