![]() |
![]() |
#1 |
Registered User
![]() Join Date: Nov 2007
Location: NLR, AR
Posts: 1,387
|
fuel economy
I know driving a classic like this, economy is not something to be truly concerned about, its more about the style. But I was wondering how many gallons per mile
![]() I just figured up, I think I'm getting around 4mpg in town. 350ci, 650cfm double pumper, th350, unknown gears, 33" tires.
__________________
2008 Sierra k3500 LMM 1994 s10 blazer 4x4 1991 Camaro Vert Rusted in Half ![]() 1972 Jimmy 4x4 L05,4L60E,np205http://67-72chevytrucks.com/vboard/s...d.php?t=546364 1967 C10 L6/3tree(dads truck) |
![]() |
![]() |
![]() |
#2 |
Registered User
Join Date: Feb 2012
Location: Durant, ok
Posts: 218
|
Re: fuel economy
Well I was under the impression I had the worst on here, everyone seems to get around 10-14 from what I've seen.
I am getting roughly 8, and I don't have enough miles on the highway to say a highway mileage. I am running a 350 SBC bored to a 355 with a th350 on 32x11.50in tiress and a 2 inch lift.
__________________
1967 SWB C-10 1972 Blazer 4x4 2011 Silverado |
![]() |
![]() |
![]() |
#3 |
Registered User
Join Date: Feb 2012
Location: Durant, ok
Posts: 218
|
Re: fuel economy
Oh and I have the 3.08 gear (3.07?); missed that one!
__________________
1967 SWB C-10 1972 Blazer 4x4 2011 Silverado |
![]() |
![]() |
![]() |
#4 |
Registered User
![]() Join Date: Nov 2007
Location: NLR, AR
Posts: 1,387
|
Re: fuel economy
I figured I would get 8-10. So the 4mpg is unexpected. I am thinking I have some steep gears since this truck was originally a 6cyl.
I used just a hair under 1/8 of a 30gal tank, to go 12 miles. |
![]() |
![]() |
![]() |
#5 |
Registered User
Join Date: Jun 2012
Location: SALT LAKE CITY, UTAH
Posts: 396
|
Re: fuel economy
I get 15mpg if I drive it nice or 8mpg hot roddin it. im runnin 350sbc sm465 with 3.73 gear 33x12.5x15 bfg all terrains. not bad I think for being a 4 speed and 42 years old
|
![]() |
![]() |
![]() |
#6 |
Registered User
Join Date: Jul 2012
Location: Lisbon ND
Posts: 111
|
Re: fuel economy
4 mpg here as well. Doesn't bother me too much except only getting 80 miles to a tank sucks!
468BB/350/205, 40x18 Boggers, 4.10 gear Planning on swapping gears to 4.88....afraid what that's going to do to the mileage! |
![]() |
![]() |
![]() |
#7 |
Registered User
Join Date: May 2011
Location: Hershey, Nebraska
Posts: 319
|
Re: fuel economy
17 mpg! haha but I did a LS swap. mixed city/highway I get around 15. 2002 5.3L/4L60E. 3:73 gears, 33 in tires. A lot better than when it had the worn out 350 in it. Got about.......6-8 haha.
__________________
Blazer Build Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=483399 |
![]() |
![]() |
![]() |
#8 |
Registered User
Join Date: May 2008
Location: 204
Posts: 903
|
Re: fuel economy
I have got as high as 17-18 last summer on the highway. Stock 350 with 130,000 miles on it, 4 spd manual new BFG 31" tires. No idea on the gears, probably the efficient kind since its as slow as a turtle off the line.
__________________
1969 Chevy Custom Camper 3/4 ton Rust free survivor 1972 Chevy Blazer CST 4x4 Almost Rust free survivor 1972 GMC Jimmy 2wd Undergoing surgery |
![]() |
![]() |
![]() |
#9 |
Registered User
![]() Join Date: Nov 2007
Location: NLR, AR
Posts: 1,387
|
Re: fuel economy
indeep, atleast yours would be a fun 4mpg!!
|
![]() |
![]() |
![]() |
#10 |
Senior Member
![]() Join Date: Jan 2001
Location: Orem, Utah
Posts: 7,912
|
Re: fuel economy
350/350 with a Quadrajet, 3.73 gears and 33 inch tires. I average 11 or so.
I'm getting it ready for a Vortec, so I'm hoping to do at least a couple of MPG better. Of course, I just got a job for after I retire from the Army, so my commute will go from 40 miles/day to about 9 - that should help too. |
![]() |
![]() |
![]() |
#11 |
Account Suspended
Join Date: May 2009
Location: Portland, OR
Posts: 89
|
Re: fuel economy
1970 - 4" lift- 35" BFG AT's - 350/TH350 - 3.73 gears - 10 mpg all day long.
Edelbrock 1406 / Performer manifold / MSD ignition / Headman long tube headers Dale99, when was the last time you went through your carb? |
![]() |
![]() |
![]() |
#12 |
Registered User
Join Date: Apr 2013
Location: Knoxville TN
Posts: 1,170
|
Re: fuel economy
As a minimum, I'd pull a plug following cruise shut down and make sure it's just off white.
Wideband O2 gauge plus carb tuning will pay for itself in short order in 4 mpg case. |
![]() |
![]() |
![]() |
#13 |
Registered User
Join Date: Aug 2012
Location: Sacramento, CA
Posts: 242
|
Re: fuel economy
LT1 350 w/ fuel injection & a 700r4, unknown gears on 38x14.50. Avg 12 MPG
Could be getting 3 MPG, still love my old girl!!
__________________
68 C10 SWB W/ 72 FRONT CLIP 343SB TH400 64 C10 SWB 406SB TH400 74 SUBURBAN 454BB TH400 78 K10 SWB 350 TH350 6" ON 35" BFG MUD 71 K5 350 W/ TBI 700R4 6" ON 38" BFG MUD 00 K3500 DRW BIG BLOCK "DRINKING PRBLM" |
![]() |
![]() |
![]() |
#14 |
Registered User
Join Date: Mar 2008
Location: Concord NC
Posts: 511
|
Re: fuel economy
1972 K5: 350/ TH350/ 3.07 gears/ 33" mud tires= 12.9mpg (35-55mph)
I havnt checked mpg's after swapping to 4.10 gears. |
![]() |
![]() |
![]() |
#15 |
Registered User
![]() Join Date: Nov 2007
Location: NLR, AR
Posts: 1,387
|
Re: fuel economy
Couple months ago when I bought this thing. I have not one single clue about carbs n how to adjust them. Id rather throw it is far as I can and bolt on some fuel injection. But I have other things to do before I go that route.
But this thread does show mine is below average which is what I was wanting to know. Tells me something is off. Now its a matter finding out if its tuning, tire alignment, friction in drive train, or my foot.... |
![]() |
![]() |
![]() |
#16 |
Registered User
Join Date: Apr 2013
Location: Knoxville TN
Posts: 1,170
|
Re: fuel economy
Could be a combo deal.
I've seen alignment off pretty bad and not affect mpg that much. If tires are snow plowing then the edges will wear fast. If clutch is slipping you'd probably notice. Late timing will impact mpg. Carb is often person of interest. Some carbs are almost fun to tune. |
![]() |
![]() |
![]() |
#17 |
Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,717
|
Re: fuel economy
70 mph KILLS fuel economy. Auto trans with no lockup converter KILLS fuel economy. When I was going to school in Lubbock I drove back and forth to Austin at least once a month. With my .030 327 (331) and SM465 with 35" tires (Mickey Thompson Baja Belteds at the time) and 4.10 gears I got 14-15 mpg. But that was when speed limit was 55... Truck still gets about same at those speeds, but falls off dramatically as speed goes over 65. Going from a Holley 750 to a Q-jet helped a lot in driveability and a tiny bit in fuel economy.
But you guys getting 8-10 (except the near 500 ci big block guys....) need to look into tuning/tweaking your combo. Should be able to squeak 12 out of it, and from 8, that's a 50% increase!!!!! ![]()
__________________
44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
![]() |
![]() |
![]() |
#18 |
Registered User
![]() Join Date: Nov 2007
Location: NLR, AR
Posts: 1,387
|
Re: fuel economy
I checked alignment a little bit ago, appears fairly good.
No clutch Timing could be an issue. I have no timing tab. Also, the drivetrain is in at an angle and the distrib rubs on the firewall constantly changing. The last part to correct all this is on its way now. Tried checking rear axle ratio. Keep coming up with about a 1.73'ish. I know thats not right, lol. I will likely work on this while fixing my drivetrain angle issue. |
![]() |
![]() |
![]() |
#19 |
Registered User
Join Date: Apr 2013
Location: Knoxville TN
Posts: 1,170
|
Re: fuel economy
|
![]() |
![]() |
![]() |
#20 | |
Registered User
Join Date: Apr 2013
Location: Knoxville TN
Posts: 1,170
|
Re: fuel economy
Quote:
Unknown timing is a big suspect. |
|
![]() |
![]() |
![]() |
#21 | |
Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,717
|
Re: fuel economy
Quote:
Here is an interesting calculator that pretty much mirrors my experience. http://www.mpgforspeed.com/ A 550 hp C6 'vette with a 6 speed can get nearly 30 mpg at 75 mph because it is amazingly aerodynamic and the motor is just idling in 6th gear. But around town it gets 16.
__________________
44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
|
![]() |
![]() |
![]() |
#22 |
Registered User
Join Date: Apr 2013
Location: Knoxville TN
Posts: 1,170
|
Re: fuel economy
I know. Just presenting an old school carb 60's car 70 mph data point with drive train technology similar to blazer.
|
![]() |
![]() |
![]() |
#23 |
Registered User
Join Date: Nov 2009
Location: Palm Beach Florida
Posts: 80
|
Re: fuel economy
|
![]() |
![]() |
![]() |
#24 |
Registered User
![]() Join Date: Aug 2010
Location: Fargo, ND
Posts: 51
|
Re: fuel economy
I believe that the holley double pumper will be dumping fuel with the primaries and secondaries everytime you give it any throttle. Where the vacuum secondary carbs will only dump fuel from the secondaries at wide open throttle.
Seems like switching from a mechanical sec carb to a vacuum sec carb could help quite a bit unless you are at WOT a lot. Just a thought? |
![]() |
![]() |
![]() |
#25 |
Registered User
![]() Join Date: Nov 2007
Location: NLR, AR
Posts: 1,387
|
Re: fuel economy
jthomass. I will take your word for it. I know nothing about carbs.
|
![]() |
![]() |
![]() |
Bookmarks |
|
|