MPG for a 402 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

JoeKan · 08-15-2009, 04:05 PM

Hello,
I'm looking at a nice looking 402 cubic inch big block with a turbo 400 tranny. Can anyone tell me what is the approx. mpg I would get out of this truck?
Thanks,
Joe

cdowns · 08-15-2009, 04:11 PM

8-10

STOCKISH · 08-15-2009, 04:13 PM

Yeah, 8-10 if you keep your foot out of it. If you're anything like me, that's hard to do.

PanelDeland · 08-15-2009, 04:50 PM

I think it will depend on the exhaust as much as anything.If it has nice quiet mufflers and very little exhaust sound than you may get 8-10 but if it sounds really good you will have your foot in it constantly which will kill your milage.

Longhorn Man · 08-15-2009, 04:52 PM

in my burb, I get more like 12 to 15 city/freeway driving. 402/Th400/3.07 gear.

JoeKan · 08-15-2009, 05:39 PM

The owner is saying that he is getting better than 12. Should I believe him?

jamesi20 · 08-15-2009, 05:54 PM

Quote:

Originally Posted by JoeKan

The owner is saying that he is getting better than 12. Should I believe him?

my old man you to say that even the most honest people you know will stretch the truth a bit on two things:1)how long it takes to get somewhere
2)the gas mileage they got gettin' there! lol!

I am sure tho that Andy is the exception to this

Longhorn Man · 08-15-2009, 11:45 PM

if it was gettin 8 MPG like every small block truck I've had, I'd tell you that too.
My one ton gets about 5 to7 MPG now... used to get 12 - 14
I ain't gonna BS anyone about anything.
The average in these trucks, across the board, is 10 - 12 acording to the opoll i took here a few years ago.
The biggest thing that makes a 9 MPG truck into a 12 MPG truck is the driver.
I used to have a POS 88 lincoln town car. My dad gave it to me, he was getting 17 - 22.... the best I could get was 13, normally it was closer to 10. He claimed it had all the power in the world, and I was pressing the pedal to find it (he was full of it, it was a worn out DOG)
So if the old man selling it says 12, and you like the torque from the pedal on the right, then expect 10 MPG.

Personally, i always say 10 MPG on these trucks. If you bank on that, then you'll usually be OK.

JoeKan · 08-16-2009, 12:10 AM

This is a beautiful looking truck but I'm going to need something that will get at least 12 on the highway. I'm a conservative driver and I don't very often punch the pedal down, so I'm not sure what kind of mpg I would get with it. Is there anything that would help it get better gas miliage besides not drive it?

maddog1331 · 08-17-2009, 12:42 AM

I had a 97 Mitsubishi Eclipse I gave to my dad a few years back. I was getting 30mpg, he got it and gets around 38. He drives it alot easier I guess and got the extra mileage.....driving style definitely makes a huge difference (and, in the Mitsubishi Eclipses I have had, it seems the spark plugs I always upgrade to make a world of difference...not sure about these chevy trucks we have though).

BCOWANWHEELS · 08-17-2009, 02:11 AM

Guess the 427 tall deck , 454 STEEL CRANK &.400 long rods with a sm465 and modern 14 bolt with 2.73 gears will be bad too in my 157"wb dually flat bed. I,ve got a nv4500 also but i really dont want it in my ton tk. I figure the sm465 with the super low 1st gear will be ok pulling out even loaded.

**70cst** · 08-17-2009, 07:49 AM

After reading this thread I have gleaned the following info: If MPG is a major concern...then our trucks are not going to offer a solution. The 402BB's will offer 8-10 average and the 350/327 will offer 13-15 on highway. The rear gears can offer some relief in improved MPG but...for the most part our trucks are great for work and play but...not for great MPG as daily drivers. JMHO. Good luck with your quest.

Longhorn Man · 08-16-2009, 12:36 AM

cool costs money... how cool do you want to be?

**70cst** · 08-16-2009, 01:43 AM

Quote:

Originally Posted by Longhorn Man

in my burb, I get more like 12 to 15 city/freeway driving. 402/Th400/3.07 gear.

Good info Andy (Thanks)...I have a 3:55 posi (I think) and it came with 3:07/3:08 gears... I think. Hey by the way...I may have another freebe for you...if you want it.

JoeKan · 08-16-2009, 04:20 PM

Would it be foolish to take out the 402 and get a more economical engine for better fuel miliage?
I don't know..it's just a thought. What do you all think?
Thanks for the help,
Joe

**70cst** · 08-16-2009, 04:30 PM

Quote:

Originally Posted by JoeKan

Would it be foolish to take out the 402 and get a more economical engine for better fuel miliage?
I don't know..it's just a thought. What do you all think?
Thanks for the help,
Joe

I'm not sure if there would be that much difference in MPG between a 327/350 verses a 402 BB. I'll let others chime in who have better experience in this area.

JoeKan · 08-16-2009, 04:51 PM

It's a camper deluxe truck that is a 3/4 ton, so it would need the power. Is there anything I could add or do to it to get better gas mileage

**SOON2BLAZE** · 08-16-2009, 05:01 PM

Quote:

Originally Posted by JoeKan

It's a camper deluxe truck that is a 3/4 ton, so it would need the power. Is there anything I could add or do to it to get better gas mileage

Try a 3K Edelbrock EFI setup, OD trans and a light pair of shoes. But again, its a BB and a 3/4 ton.

QKENUF4U · 08-16-2009, 04:30 PM

my brother used to get 15+ out of his 4-speed/427 nova on his trips from vir. beach to pennsylvania....
i only got 8-10 outta my 402 in my 71 prostreet truck.....

Longhorn Man · 08-16-2009, 05:30 PM

or a honda maybe.
If you can't afford to drive one, or don't want to afford it, then there's no point in doing it.
if you add fuel injection, or an overdrive, or anything like that, you'll spend 4 or 5 years of gas money to get the improvement.

mclairmo · 08-16-2009, 06:50 PM

Buy a honda if you want MPG. No old truck is going to give you good MPG. What's the difference bewteen 10 MPG or 12 MPG or 8 MPG, they all suck compared to new cars. If you want a cool old Big Block truck, then relatively bad MPG is the price you pay. If you have to ask how you can get more mileage out of a Big Block, then you should not get one. My 396 gets horrible mileage, so bad I never even tried to measure it. I don't care, though. Gas is cheap here, compared to the rest of the world. I say burn it while we can.

stumpy · 08-16-2009, 07:18 PM

Did you say you were looking for a 402/TH400 combo?

http://www.impalassforum.com/vBullet...d.php?t=227454

Longhorn Man · 08-16-2009, 07:28 PM

no one said that... no.

CPNEJR · 08-16-2009, 09:51 PM

well my brothers 402 got 8-10 and i just took my truck to pennsylvania for the all truck nationals and i got 16 mpg the whole way with a 350 3OTT with 3.08 gears. all driving was on the interstate at 75-80 mph. but my truck is also a 1/2 ton shortbed.

**nbrfd007** · 08-16-2009, 10:00 PM

Get around 10, worth everybit of it. Great to have the power when you need it.

08-15-2009, 04:05 PM	#1
JoeKan Registered User Join Date: Jul 2008 Location: Kansas Posts: 707	MPG for a 402 Hello, I'm looking at a nice looking 402 cubic inch big block with a turbo 400 tranny. Can anyone tell me what is the approx. mpg I would get out of this truck? Thanks, Joe

08-15-2009, 04:11 PM	#2
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: MPG for a 402 8-10 __________________ 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

08-15-2009, 04:13 PM	#3
STOCKISH Formerly- 1972SuperCheyenne Join Date: Oct 2008 Location: Wake Forest NC Posts: 5,782	Re: MPG for a 402 Yeah, 8-10 if you keep your foot out of it. If you're anything like me, that's hard to do. __________________ --Josh My Build Thread:http://67-72chevytrucks.com/vboard/s...d.php?t=799218 A good crossthread is better than Loctite any day. Life is not about what you have, but who you have to share it with.

08-15-2009, 04:50 PM	#4
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Re: MPG for a 402 I think it will depend on the exhaust as much as anything.If it has nice quiet mufflers and very little exhaust sound than you may get 8-10 but if it sounds really good you will have your foot in it constantly which will kill your milage. __________________ The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil"

08-15-2009, 04:52 PM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: MPG for a 402 in my burb, I get more like 12 to 15 city/freeway driving. 402/Th400/3.07 gear.

08-15-2009, 05:39 PM	#6
JoeKan Registered User Join Date: Jul 2008 Location: Kansas Posts: 707	Re: MPG for a 402 The owner is saying that he is getting better than 12. Should I believe him?

08-15-2009, 11:45 PM	#8
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: MPG for a 402 if it was gettin 8 MPG like every small block truck I've had, I'd tell you that too. My one ton gets about 5 to7 MPG now... used to get 12 - 14 I ain't gonna BS anyone about anything. The average in these trucks, across the board, is 10 - 12 acording to the opoll i took here a few years ago. The biggest thing that makes a 9 MPG truck into a 12 MPG truck is the driver. I used to have a POS 88 lincoln town car. My dad gave it to me, he was getting 17 - 22.... the best I could get was 13, normally it was closer to 10. He claimed it had all the power in the world, and I was pressing the pedal to find it (he was full of it, it was a worn out DOG) So if the old man selling it says 12, and you like the torque from the pedal on the right, then expect 10 MPG. Personally, i always say 10 MPG on these trucks. If you bank on that, then you'll usually be OK.

08-16-2009, 12:10 AM	#9
JoeKan Registered User Join Date: Jul 2008 Location: Kansas Posts: 707	Re: MPG for a 402 This is a beautiful looking truck but I'm going to need something that will get at least 12 on the highway. I'm a conservative driver and I don't very often punch the pedal down, so I'm not sure what kind of mpg I would get with it. Is there anything that would help it get better gas miliage besides not drive it?

08-17-2009, 12:42 AM	#10
maddog1331 Registered User Join Date: Feb 2009 Location: Somerset, KY Posts: 398	Re: MPG for a 402 I had a 97 Mitsubishi Eclipse I gave to my dad a few years back. I was getting 30mpg, he got it and gets around 38. He drives it alot easier I guess and got the extra mileage.....driving style definitely makes a huge difference (and, in the Mitsubishi Eclipses I have had, it seems the spark plugs I always upgrade to make a world of difference...not sure about these chevy trucks we have though).

08-17-2009, 02:11 AM	#11
BCOWANWHEELS Registered User Join Date: Nov 2006 Location: KINGSPORT,TN. Posts: 3,035	Re: MPG for a 402 Guess the 427 tall deck , 454 STEEL CRANK &.400 long rods with a sm465 and modern 14 bolt with 2.73 gears will be bad too in my 157"wb dually flat bed. I,ve got a nv4500 also but i really dont want it in my ton tk. I figure the sm465 with the super low 1st gear will be ok pulling out even loaded. __________________ I BELIEVE IN JOHN 3:16 Last edited by BCOWANWHEELS; 08-17-2009 at 02:12 AM.

08-17-2009, 07:49 AM	#12
70cst Senior Member Join Date: Feb 2001 Location: New Madison, Ohio Posts: 21,363	Re: MPG for a 402 After reading this thread I have gleaned the following info: If MPG is a major concern...then our trucks are not going to offer a solution. The 402BB's will offer 8-10 average and the 350/327 will offer 13-15 on highway. The rear gears can offer some relief in improved MPG but...for the most part our trucks are great for work and play but...not for great MPG as daily drivers. JMHO. Good luck with your quest. __________________ A husband can be right...or...A husband can be happy. 67-72 Chevy and GMC Trucks...The Classic Truck for the Classic Folk. 1970 CST Two tone green, 402BB, 400 Automatic, Tach, Buckets, AC, AM-FM, Tilt, GM CB, GM 8 Tract, LWB, etc JOHN 17:3...The better side of "LIFE" Remember: Everyday is a good day...Some are just gooder!

08-16-2009, 12:36 AM	#13
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: MPG for a 402 cool costs money... how cool do you want to be?

08-16-2009, 04:20 PM	#15
JoeKan Registered User Join Date: Jul 2008 Location: Kansas Posts: 707	Re: MPG for a 402 Would it be foolish to take out the 402 and get a more economical engine for better fuel miliage? I don't know..it's just a thought. What do you all think? Thanks for the help, Joe

08-16-2009, 04:51 PM	#17
JoeKan Registered User Join Date: Jul 2008 Location: Kansas Posts: 707	Re: MPG for a 402 It's a camper deluxe truck that is a 3/4 ton, so it would need the power. Is there anything I could add or do to it to get better gas mileage

08-16-2009, 04:30 PM	#19
QKENUF4U Senior Member Join Date: Jan 2005 Location: SUNNY WARM BIKE RIDING COTTONWOOD ARIZONA Posts: 2,097	Re: MPG for a 402 my brother used to get 15+ out of his 4-speed/427 nova on his trips from vir. beach to pennsylvania.... i only got 8-10 outta my 402 in my 71 prostreet truck.....



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08-16-2009, 05:30 PM	#20
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: MPG for a 402 or a honda maybe. If you can't afford to drive one, or don't want to afford it, then there's no point in doing it. if you add fuel injection, or an overdrive, or anything like that, you'll spend 4 or 5 years of gas money to get the improvement.

08-16-2009, 06:50 PM	#21
mclairmo Registered User Join Date: Jan 2006 Location: Take Off Posts: 1,908	Re: MPG for a 402 Buy a honda if you want MPG. No old truck is going to give you good MPG. What's the difference bewteen 10 MPG or 12 MPG or 8 MPG, they all suck compared to new cars. If you want a cool old Big Block truck, then relatively bad MPG is the price you pay. If you have to ask how you can get more mileage out of a Big Block, then you should not get one. My 396 gets horrible mileage, so bad I never even tried to measure it. I don't care, though. Gas is cheap here, compared to the rest of the world. I say burn it while we can. Last edited by mclairmo; 08-16-2009 at 06:50 PM.

08-16-2009, 07:18 PM	#22
stumpy Registered User Join Date: Dec 2007 Location: Downingtown, PA Posts: 22	Re: MPG for a 402 Did you say you were looking for a 402/TH400 combo? http://www.impalassforum.com/vBullet...d.php?t=227454 __________________ 67 C10 LWB Fleet 02 Chevy K1500HD Crew Cab - Stock LQ4 & 4L80E, 3.73's, my DD 08 Impala SS - Wife's DD 96 Impala SS - stock engine with bolt-ons(Wifes race car), 96 Impala SS - 496 BBC race car 9.69 @ 143

08-16-2009, 07:28 PM	#23
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: MPG for a 402 no one said that... no.

08-16-2009, 09:51 PM	#24
CPNEJR Registered User Join Date: Sep 2003 Location: Franconia,N.H. Posts: 1,029	Re: MPG for a 402 well my brothers 402 got 8-10 and i just took my truck to pennsylvania for the all truck nationals and i got 16 mpg the whole way with a 350 3OTT with 3.08 gears. all driving was on the interstate at 75-80 mph. but my truck is also a 1/2 ton shortbed. __________________ (Only) Member of the CPNE Fan Club Aint that the truth 67 C-10 350 with 3-speed tranny and 308 gears swb step 82 Z28 Camaro 355 small block over 350 hp and a borg warner super t-10 (blown engine) 72 Chevy K20 Suburban (future project) 70 Chevy K20 now 68 GMC K2500 2003 Chevy 2500hd ccsb 4X4 (daily driver)

08-16-2009, 10:00 PM	#25
nbrfd007 Senior Member Join Date: Nov 2007 Location: New Blaine, Arkansas Posts: 751	Re: MPG for a 402 Get around 10, worth everybit of it. Great to have the power when you need it.

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