What is the best mileage anybody has ever got /highway/around town with a carburated - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ubtripn · 06-12-2011, 04:07 PM

350 (Had to finish the title of the threa.)

I asked this along time ago and got a lot of - "It's not about the mileage" or "if you have to ask responses." With those thoughts aside, I am just curious as I am finishing up my truck. I know that EFI helps and the newer 350's are more efficient but what about the best mileage out of an older, carburated 350?

I am not going to get a Geo or Rabbit to drive around daily and then just drive my truck for fun. One of the things I love about my 68 is that it fits me perfectly in terms of space, comfort, functionality and simplicity. I will be using it as my daily driver and it will be cheaper than buying a new truck because I won't have a truck payment or full coverage. So, what can one expect if they do the right things to a carbed 350? thx in advance.

67ChevyRedneck · 06-12-2011, 04:31 PM

How about "there sure are a hell of a lot of variables..."

My scenario... stockish 350 with HEI and 650 cfm edelbrock backed by a 700R4 with a 3.73 rear end.

Depending on how happy my right foot is I get between 10-12mpg around town (very little OD use).

I've gotten as high as 16.5 on a straight highway trip averaging around 60mph. I've also gotten as low as 14.5-15mpg averaging around 70-75mph. I've checked/verified my mph and odometer with GPS several times so I feel my numbers are actually accurate

bobs409 · 06-12-2011, 05:57 PM

The last time I bothered to check gas mileage I got close to 16 mpg (15.9 to be exact) with my 69 short stepside that has a 350/TH350/3.73 rear gear. That's in town. Forget the highway, it's probably less with the rear gear.

My truck weighs approx. 3900 lbs.

I checked my 72 Chevelle that had a 307/TH350/2.73 rear gear at that same time and it did a little better at a strong 16 mpg. (in town)

Mike Bradbury · 06-12-2011, 06:21 PM

I have a th400 now with a 650 CFM carb and 3.50 rear gear and I am happy when I get 11. That is usually mixed driving freeway and town. I have a 700r4 that is waiting to go in and hopefully I can get in the teens.

fastwillie 696969 · 06-12-2011, 06:25 PM

dont ask me i get about 4 mpg

bmfm64 · 06-12-2011, 06:32 PM

70 SWB with a 350 with aprox 275k miles on it with a performer intake, carter 600 and K&N filter/ TH350 with 12 bolt with 3:73 and 15 inch rallys with 60 series... Around town if I drive like I should I can get around 8-10 on the freeway at 60ish I can pull around 14-16.

slotdad · 06-12-2011, 06:40 PM

1972 c-20 350 w/ quadrajet, all stock,never got better than 14 hiway. Big rear gears do hurt me. Have tried 3 different q-jets, same result.

mpotts64 · 06-12-2011, 06:51 PM

'68 short step with a 283, 700R, and 17" tires and get about 14 on the road, less in town, I have a bad set up, almost no top end, so I am sure that does not help any, also have a '68 lwb with a 350 and 700R, it gets about 12-13 on the highway, less in town

67_C-30 · 06-12-2011, 06:51 PM

I used to get about 14 - 15 in with my '69 SWB fleet 350/TH350/3.08 and about 16 - 17 on the interstate. I ran it around 75 - 80 on the interstate, and I'm sure that's why highway mileage really wasn't better than in town.

I can tell you one thing with certainty. You are going to have to run a good, fresh Q-jet to get optimum mileage. I've ran tons of Holleys, Edelbrocks, and Carters, and they run good, but can't touch a good Q jet.

yuccales · 06-12-2011, 07:35 PM

12 mpg. Up hill, down hill, loaded, unloaded, thats what she gets! Glad I don't have a long drive to work.

ubtripn · 06-12-2011, 09:26 PM

Thank you all for such great examples, that helps alot. It sounds pretty difficult to break th 20's mark. Your right, there are a lot of variables but I wanted to get some ideas, thanks again.

67_C-30 · 06-12-2011, 09:35 PM

Quote:

Originally Posted by ubtripn

Thank you all for such great examples, that helps alot. It sounds pretty difficult to break th 20's mark. Your right, there are a lot of variables but I wanted to get some ideas, thanks again.

I would think a truck with an OD trans and a Q jet come closest to getting 20 mpg if you are staying carbureted.

coops714x4 · 06-12-2011, 09:48 PM

I had a 68 lwb 350/sm465 with a 3.08 rear end on TALL 15"s , if I drove it right "keeping my foot out of it " I would average 17 mpg and on the highway at about 2500 rpm on a good day I have gotten 22 mpg "man I wish I would have kept that truck"

67ChevyRedneck · 06-12-2011, 10:43 PM

Quote:

Originally Posted by ubtripn

Thank you all for such great examples, that helps alot. It sounds pretty difficult to break th 20's mark. Your right, there are a lot of variables but I wanted to get some ideas, thanks again.

It's not easy pushing a 4,000 lb brick down the highway...

I think the best fuel mileage would be from a 4.8/5.3 in stock form with the 4L60 and a 3.40s something rear, but all that alone and everything to make it work ain't cheap. It might hit 20 on the highway if you take it easy but it's still probably only going to get 13-14 around town.

GASoline71 · 06-12-2011, 10:47 PM

My truck is my play truck... 425hp SBC... I'm lucky if I get 8 mpg on a good day. If I've always got my foot in it... then around 5 mpg.

Gary

ubtripn · 06-12-2011, 10:53 PM

Thanks. I have a 350, Edlebrock 650 and I am ashamed to say that I have no idea of my rearend.

I had someone tell me once that a 4 barrel carb is more economical as long as you keep your foot out of it because the primaries are smaller than the mains on a two barrel. Is that true?

GASoline71 · 06-12-2011, 11:01 PM

Two barrels have to "work harder". So you have to put your foot in it more. A four barrel makes up for it with the second set of barrels. So you don't have to put your foot in it as much to work the same load.

Gary

ubtripn · 06-12-2011, 11:20 PM

I see, I had always thought it was about not opening up your secondaries. (For Economy) Good to know.

Dano69c10 · 06-12-2011, 11:25 PM

70 c10; 350 sbc V-8, 4 bbl EBrock, 3:73 gears, th-350 - 13 mpg

Frkypunk70 · 06-12-2011, 11:26 PM

350/350 3.08 rear 10-12 might be the cam timing or my foot though
Posted via Mobile Device

Indyuke · 06-13-2011, 01:52 PM

The best i've gotten is 18mpg on the highway. The formula for that is:

Stock 350
HEI
Q-jet
700r4 Trans
3.73 rear
skinny tires aired up to 40psi
and... keeping the speed at 55mph

But for the most part I get about 15-16 on the highway and 12-13 in town.

Classic69 · 06-13-2011, 02:46 PM

1969 C/10 Longbed, SBC V8, TH350, 4 bbl Q-Jet, HEI, 4.56 gears = 10 to 12 mpg

Myself · 06-13-2011, 04:21 PM

Maybe not the most fuel efficient combo with the carb, but it's all about the SMILES per gallon!!

Classic69 · 06-13-2011, 05:10 PM

Quote:

Originally Posted by Myself

....but it's all about the SMILES per gallon!!

X2

**JJorgensen52** · 06-13-2011, 06:53 PM

I have a 307 2bbl with a NV4500 and 3.73s running 31" tires. I get about 10mpg around town and I've seen 14mpg on the highway if I'm cruising 70-75 and get into overdrive. That little 2bbl spends a lot of time wide open to get the truck moving, I'll tell you that. Going to a Q-jet when I rebuild the motor.

06-12-2011, 04:07 PM	#1
ubtripn Registered User Join Date: Apr 2010 Location: Boise, ID Posts: 1,280	What is the best mileage anybody has ever got /highway/around town with a carburated 350 (Had to finish the title of the threa.) I asked this along time ago and got a lot of - "It's not about the mileage" or "if you have to ask responses." With those thoughts aside, I am just curious as I am finishing up my truck. I know that EFI helps and the newer 350's are more efficient but what about the best mileage out of an older, carburated 350? I am not going to get a Geo or Rabbit to drive around daily and then just drive my truck for fun. One of the things I love about my 68 is that it fits me perfectly in terms of space, comfort, functionality and simplicity. I will be using it as my daily driver and it will be cheaper than buying a new truck because I won't have a truck payment or full coverage. So, what can one expect if they do the right things to a carbed 350? thx in advance. Last edited by ubtripn; 06-12-2011 at 04:09 PM.

06-12-2011, 04:31 PM	#2
67ChevyRedneck Hittin E-Z Street on Mud Tires Join Date: Nov 2004 Location: Greenville, SC Posts: 23,090	Re: What is the best mileage anybody has ever got /highway/around town with a carbura How about "there sure are a hell of a lot of variables..." My scenario... stockish 350 with HEI and 650 cfm edelbrock backed by a 700R4 with a 3.73 rear end. Depending on how happy my right foot is I get between 10-12mpg around town (very little OD use). I've gotten as high as 16.5 on a straight highway trip averaging around 60mph. I've also gotten as low as 14.5-15mpg averaging around 70-75mph. I've checked/verified my mph and odometer with GPS several times so I feel my numbers are actually accurate __________________ Jesse James 1967 C10 SWB Stepside: 350/700R4/3.73 1965 Ford Mustang: 289/T5-5spd/3.25 Trac-Loc 1968 Pontiac Firebird: Project Fire Chicken! 2015 Silverado Double Cab 5.3L Z71 2001 Jeep Wrangler Sport 4.0L 5spd 2020 Chevrolet Equinox Premium 2.0L Turbo 2011 Mustang V6 ~ Wife's ride American Born, Country by the Grace of God 1967 CST Shop Truck Rebuild! My 1967 C-10 Build Thread My Vintage Air A/C Install Project "On a Dime" Trying my hand at Home Renovation! 1965 Mustang Modifications! Last edited by 67ChevyRedneck; 06-12-2011 at 04:35 PM.

06-12-2011, 05:57 PM	#3
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	Re: What is the best mileage anybody has ever got /highway/around town with a carbura The last time I bothered to check gas mileage I got close to 16 mpg (15.9 to be exact) with my 69 short stepside that has a 350/TH350/3.73 rear gear. That's in town. Forget the highway, it's probably less with the rear gear. My truck weighs approx. 3900 lbs. I checked my 72 Chevelle that had a 307/TH350/2.73 rear gear at that same time and it did a little better at a strong 16 mpg. (in town) __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

06-12-2011, 06:21 PM	#4
Mike Bradbury Registered User Join Date: Apr 2008 Location: San Diego California Posts: 1,316	Re: What is the best mileage anybody has ever got /highway/around town with a carbura I have a th400 now with a 650 CFM carb and 3.50 rear gear and I am happy when I get 11. That is usually mixed driving freeway and town. I have a 700r4 that is waiting to go in and hopefully I can get in the teens. __________________ I'd rather attempt something great and fail.. than try something ordinary and succeed. Norman Vincent Peale Project: Barn Raising http://67-72chevytrucks.com/vboard/s...d.php?t=414961 Project: 30 Be Low https://67-72chevytrucks.com/vboard/...d.php?t=830583

06-12-2011, 06:25 PM	#5
fastwillie 696969 ~Rest In Peace~ Join Date: May 2005 Location: CALIFORNIA NOR CAL Posts: 9,707	Re: What is the best mileage anybody has ever got /highway/around town with a carbura dont ask me i get about 4 mpg __________________ is it fast ? it has a lighting bolt donut? B___H please, I can remove 90% of your so called "beauty" with a kleenex

06-12-2011, 06:32 PM	#6
bmfm64 Registered User Join Date: May 2011 Location: Covington, Wa Posts: 5,240	Re: What is the best mileage anybody has ever got /highway/around town with a carbura 70 SWB with a 350 with aprox 275k miles on it with a performer intake, carter 600 and K&N filter/ TH350 with 12 bolt with 3:73 and 15 inch rallys with 60 series... Around town if I drive like I should I can get around 8-10 on the freeway at 60ish I can pull around 14-16.

06-12-2011, 06:40 PM	#7
slotdad Registered User Join Date: May 2011 Location: carlisle, pa Posts: 7	Re: What is the best mileage anybody has ever got /highway/around town with a carbura 1972 c-20 350 w/ quadrajet, all stock,never got better than 14 hiway. Big rear gears do hurt me. Have tried 3 different q-jets, same result.

06-12-2011, 06:51 PM	#8
mpotts64 Registered User Join Date: Mar 2011 Location: Texarkana, AR Posts: 123	Re: What is the best mileage anybody has ever got /highway/around town with a carbura '68 short step with a 283, 700R, and 17" tires and get about 14 on the road, less in town, I have a bad set up, almost no top end, so I am sure that does not help any, also have a '68 lwb with a 350 and 700R, it gets about 12-13 on the highway, less in town __________________ No one ever fell to the top of a mountain. When asked why I work on old trucks, I tell them: Been married 27 years, sons are pretty much gone, don't like the wife anymore and don't have a girlfriend, so, gotta do something, the old trucks are cheaper and less drama than a girlfriend - Last edited by mpotts64; 06-12-2011 at 06:55 PM.

06-12-2011, 06:51 PM	#9
67_C-30 I have a radical idea! Join Date: Jan 2005 Location: Sweet Home Alabama! Posts: 6,513	Re: What is the best mileage anybody has ever got /highway/around town with a carbura I used to get about 14 - 15 in with my '69 SWB fleet 350/TH350/3.08 and about 16 - 17 on the interstate. I ran it around 75 - 80 on the interstate, and I'm sure that's why highway mileage really wasn't better than in town. I can tell you one thing with certainty. You are going to have to run a good, fresh Q-jet to get optimum mileage. I've ran tons of Holleys, Edelbrocks, and Carters, and they run good, but can't touch a good Q jet. __________________ '67 C-30 Dually Pickup 6.2 Turbo Diesel, NP435 ‘72 C-10 SWB , 350 4bbl, TH350 '69 C-10 SWB , 250 L6, 3 OTT '69 GMC C3500, dump truck, 351 V6, NP435 '84 M1009 CUCV Military Blazer 67 C-30 Turbodiesel build thread http://67-72chevytrucks.com/vboard/s...d.php?t=254096 My trucks http://s226.photobucket.com/albums/d...ediafilter=all Member of the 1-Ton Club!

06-12-2011, 07:35 PM	#10
yuccales Registered User Join Date: May 2011 Location: Northern Calif. Posts: 3,777	Re: What is the best mileage anybody has ever got /highway/around town with a carbura 12 mpg. Up hill, down hill, loaded, unloaded, thats what she gets! Glad I don't have a long drive to work.

06-12-2011, 09:26 PM	#11
ubtripn Registered User Join Date: Apr 2010 Location: Boise, ID Posts: 1,280	Re: What is the best mileage anybody has ever got /highway/around town with a carbura Thank you all for such great examples, that helps alot. It sounds pretty difficult to break th 20's mark. Your right, there are a lot of variables but I wanted to get some ideas, thanks again.

06-12-2011, 09:48 PM	#13
coops714x4 Registered User Join Date: Mar 2011 Location: Cement Oklahoma Posts: 916	Re: What is the best mileage anybody has ever got /highway/around town with a carbura I had a 68 lwb 350/sm465 with a 3.08 rear end on TALL 15"s , if I drove it right "keeping my foot out of it " I would average 17 mpg and on the highway at about 2500 rpm on a good day I have gotten 22 mpg "man I wish I would have kept that truck" __________________ 1971 K20, Coop's beast (project) 1972 C30 wrecker, "Big Ernest" (SOLD) 1975 K5 Blazer (wife's toy) she got it in the divorce 2014 Street Glide Special 1983 K20 Big Block, auto (work horse)

06-12-2011, 10:53 PM	#16
ubtripn Registered User Join Date: Apr 2010 Location: Boise, ID Posts: 1,280	Re: What is the best mileage anybody has ever got /highway/around town with a carbura Thanks. I have a 350, Edlebrock 650 and I am ashamed to say that I have no idea of my rearend. I had someone tell me once that a 4 barrel carb is more economical as long as you keep your foot out of it because the primaries are smaller than the mains on a two barrel. Is that true?

06-12-2011, 11:20 PM	#18
ubtripn Registered User Join Date: Apr 2010 Location: Boise, ID Posts: 1,280	Re: What is the best mileage anybody has ever got /highway/around town with a carbura I see, I had always thought it was about not opening up your secondaries. (For Economy) Good to know.

06-12-2011, 11:25 PM	#19
Dano69c10 Senior Member Join Date: Jan 2005 Location: Ontario, Kali Posts: 2,427	Re: What is the best mileage anybody has ever got /highway/around town with a carbura 70 c10; 350 sbc V-8, 4 bbl EBrock, 3:73 gears, th-350 - 13 mpg __________________ '69 Fleet It ain't yours, if you didn't build it! Last edited by Dano69c10; 06-14-2011 at 05:38 PM.



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06-12-2011, 11:26 PM	#20
Frkypunk70 Registered User Join Date: Mar 2010 Location: Scranton,Pa Posts: 423	Re: What is the best mileage anybody has ever got /highway/around town with a carbura 350/350 3.08 rear 10-12 might be the cam timing or my foot though Posted via Mobile Device __________________ "When I die, I want to go peacefully like my Grandfather did, in his sleep -- not screaming, like the passengers in his car. "

06-13-2011, 01:52 PM	#21
Indyuke Registered User Join Date: Feb 2008 Location: Lake Stevens, WA Posts: 623	Re: What is the best mileage anybody has ever got /highway/around town with a carbura The best i've gotten is 18mpg on the highway. The formula for that is: Stock 350 HEI Q-jet 700r4 Trans 3.73 rear skinny tires aired up to 40psi and... keeping the speed at 55mph But for the most part I get about 15-16 on the highway and 12-13 in town.

06-13-2011, 02:46 PM	#22
Classic69 Love That '69 Join Date: Oct 2007 Location: Sherwood Park, Alberta, Canada Posts: 360	Re: What is the best mileage anybody has ever got /highway/around town with a carbura 1969 C/10 Longbed, SBC V8, TH350, 4 bbl Q-Jet, HEI, 4.56 gears = 10 to 12 mpg __________________ *I AM CANADIAN!!!!!* 1969 Chevy C/10 Truck - SBC V8, TH-350, 3.73 Posi, 1000W Rockford Fosgate Stereo System, B&M Megashifter, GT Grant Steering Wheel, Dual Magnaflow Exhaust System, Dynomax Headers, Lowered 1" Front & 3" Rear, Front/Rear Sway Bars, Racing Seats, 6000K HID Headlights 2008 Chevy Colorado LT - 3.7L I5, 4 Speed Automatic, Crew Cab, 4X4, Z71 Off-Road Package, "Ground Effects" Package, K&N Cold Air Intake, Supermod PTB, Magnaflow Exhaust w/ Resonator, 500W Kenwood / Rockford Fosgate Stereo System, Custom LED Lighting, 6000K HID Low's / High's, Blackcat Customs Gauges / Needles, Carbon Fiber Interior Accents, KrFabs 2" Lift Shackles / Torsion Bar Crank with Rancho RS5000 Shocks, Superskids Skid Plates Last edited by Classic69; 06-13-2011 at 02:51 PM.

06-13-2011, 04:21 PM	#23
Myself Registered User Join Date: Oct 2005 Location: Northern Arkansas Posts: 1,144	Re: What is the best mileage anybody has ever got /highway/around town with a carbura Maybe not the most fuel efficient combo with the carb, but it's all about the SMILES per gallon!!

06-13-2011, 06:53 PM	#25
JJorgensen52 Simple? What's simple? Join Date: Apr 2007 Location: Southeast CT Posts: 1,472	Re: What is the best mileage anybody has ever got /highway/around town with a carbura I have a 307 2bbl with a NV4500 and 3.73s running 31" tires. I get about 10mpg around town and I've seen 14mpg on the highway if I'm cruising 70-75 and get into overdrive. That little 2bbl spends a lot of time wide open to get the truck moving, I'll tell you that. Going to a Q-jet when I rebuild the motor. __________________ CURRENT '50 GMC 100 shortbed Gen IV 4.8 LS - 4L65E (Secret truck, Shhh!!!) Build '63 Buick Wildcat Coupe 401ci Nailhead (Very much in pieces) Photos '66 Impala SS convertible 327-QJet-glide (4 speed swap one of these days...) Photos '69 CST/10 4x4 SWB Stepper 350 2bbl - NV4500/NP241C (Broken Truck!) '72 Sierra Grande 2WD LWB fleetside 350-TH350 Refresh '99 K2500 Silverado RCLB 5.7 Vortec - NV4500/NP241C (Daily) '99 K2500 Suburban 7.4 Vortec - NV4500/NP246 (still working out the bugs) SOLD '71 Custom/10 2WD LWB fleetside - '72 GMC K/3500 Dually (Sold to redryder)

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