Inline six gas mileage? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Dwaynes56&68 · 08-29-2003, 04:37 AM

I am considering swapping a 250 in place of my worn out 350. Is there a slim chance that gas mileage will be better or will it bite the dust cause the motor will be working harder. I also found a complete 292 good runner for 250 bucks. Is the 292 a better option then the 250?

**'68OrangeSunshine** · 08-29-2003, 05:29 AM

The 292 is a work truck engine. Very strong. Its virtues are big torque at low RPM, longevity/durability and heat tolerance. It does not turn fast. 4500 -5000 is redline for a stock 292.
The 250 might run faster but I have no experience with them first hand so it would be unfair for me to venture a biased opinion.
292's are a lot of fun. I ran one in my '68 C/10 shortbed stepside with a 4 Bbl Holley, Offy intake, Clifford headers on a .030 bore from '77 to '02. I'm now in the process of finishing a rebuild of the original 292 block and I just picked up an early ('63?) 292 L6 as a parts carcass.
You might ask the 250 vs 292 question at:
www.inliners.org
Hope this helps

MOTHERTRUCKERS · 08-29-2003, 07:15 AM

Do you know the 63 292 is the only year with a forged steel crankshaft

dubie · 08-29-2003, 09:17 AM

I used to get pretty decent mileage out of my 250 inline. ON the highway I got about 19 MPG and about 17 around town. It was backed by a 3 speed manual

Brad · 08-29-2003, 10:19 AM

At one point I could get as high as 18mpg in the truck, but that was very rare. Usually it was around 16. I haven't put any time or energy into maintanence and it's getting around 12mpg right now.
The Camaro has gotten up to 25mpg on the highway!

oldsub86 · 08-29-2003, 10:53 AM

I wouldn't say that mileage was its strong point but I have had my 292 for a long time and it has been a good motor. I used to have a 250 in a '67 shortbox stepside and I think the 292 is a much better motor. Mostly subjective I guess rather than objective as I can't tell you in detail why. I also have to admit that my 250 was about worn out and the 292 is in better condition. I like the 292 and if you want to be different, an inline is it. There is not as much aftermarket stuff readily available and the stuff that is out there will cost more. If you plan to leave it stock that will not be a problem.

**truckster** · 08-29-2003, 11:01 AM

I have a 250 in my truck temporarily. I don't think you'd see any improvement in mileage. I get about 14. The 250 just isn't big enough for one of these trucks. It does have one interesting characteristic, though. It sounds like the old UPS truck when I accelerate.

**'68OrangeSunshine** · 08-29-2003, 04:00 PM

Quote:

Originally posted by MOTHERTRUCKERS
Do you know the 63 292 is the only year with a forged steel crankshaft

Yes, I read that in Leo Santucci's book. I'm running the engine serial at www.inliners.org to see if it really is a '63. It has the earlier oilpan w/ many bolts to the timing gear cover, and is a wierd green-blue. [Robin's Egg Blue?] unlike the '67 and later which are Chevy Orange.
FIII6PG is stamped on the distributor pad.
Sorry, I didn't mean to hijack the thread.

Fred T · 08-29-2003, 06:35 PM

I've had several 250s. They have adequate power, but you sure won't win any races unless you spend a lot of bucks. Talked to a guy with one in a early Nova with dual Holley quads who was turning low 12's.

Milage can vary, anywhere from 15 to 20 mpg, depends on a lot. My best milage was in an 80 van that had the integral head and a progressive 2 bbl carb.

The 292 will give more power, lots of torque at the bottom end. I've never owned one, but do have one in the plans for my 52. I would assume that with more cubic inches, the milage will suffer some, but don't know how much.

jhwkns · 08-29-2003, 07:14 PM

I had a 67 with a 250 in it some years back... It was a lot quicker than my dads 84 which was new at the time... but that ain't sayin' much

palallin · 08-29-2003, 11:24 PM

My wife a 250 in her '66 Bel Air (w/ a PG). It would run on the highway all day long, but it took all morning to get up to highway speed. Mileage was poor, but I don't remember exact figures.

PanelDeland · 08-30-2003, 07:59 AM

Most of the 6's were equipted like a farm truck.3 or 4 speeds and low rear gears.If you run an auto and maybe some decent gearing you could get decent milage.The 6's run much lower RPM's so don't expect much performance.I have a 250-3sp-3.73 and I get about 13-15 but at 65 she's pretty well wound up.I hope to swap to 3.08's and later on maybe a 700R4 or 480L.
I think the uniqueness of the 6 is important if you want to drive something different from a jellybean.

Dwaynes56&68 · 08-30-2003, 10:34 AM

hmm, still sounds like the 6 gets better mileage then a 350. Even when mine was still in good shape it never did better then 12 mpg. Thats with 3:73 gears and 31 inch tires, auto etc. I bought the 292. The guy was selling it cheap but I tried to knock a few bucks off by commenting on the leaky front seal etc. And he was like give me a hundred and I pull it. Done deal

The best part is he is letting me take all the brackets and mounts as it is coming out of a 71 truck. Anyways, the motor has a single barrel carb that looks like its seen better days. I have decided that since this motor is going in I am going to invest in a gasket kit and a exhaust and intake upgrade. I do not plan on trying to build massive power but I think a 2 barrel and a header would help. was there a factory 2 barrel intake that will bolt on? If so what truck/ car would be the place to look?

PanelDeland · 08-30-2003, 11:33 AM

Dwyne, as far as I know there was never a 2 bbl 6 cyl factory offering.You can visit Cliffords performance for a 4bbl intake that uses a 390CFM Holley.That upgrade will probably run around $500.00 new.For around another $250.00 you can get a header.
6cyl. performance ain't as cheap as the 'ole smallblock as you can see.
If time is a factor, swap in the complete 6 and hit the swap meets for a manifold and carb. I see a guy here in the Atlanta area that carries a lot of 6 performance stuff but it may be harder to locate where you are.

inlinersinternational.com is the place to ask 6 cyl performance questions.Maybe someone over ther will have some used stuff or a better deal.

**'68OrangeSunshine** · 08-31-2003, 07:31 AM

Quote:

Originally posted by Dwaynes56&68
hmm, ... was there a factory 2 barrel intake that will bolt on? If so what truck/ car would be the place to look?

Factory 2 barrel intake?. No. not in this country, but GM did release one in South America. GM casting # 2793490. Be real funny if you could order one thru GM performance Parts. I'm dreaming. Clifford makes one: p/n 42-4501.

rustyold69 · 08-31-2003, 12:42 PM

In 1980 the straight six with the integral head had a 2 barrel carb on it and it had a dual exhaust manifold.

**'68OrangeSunshine** · 09-01-2003, 04:56 AM

You're right, but my head is still in the late '60s/ early '70s.

08-29-2003, 04:37 AM	#1
Dwaynes56&68 Registered User Join Date: Aug 2003 Location: Crawfordsville,Oregon Posts: 83	Inline six gas mileage? I am considering swapping a 250 in place of my worn out 350. Is there a slim chance that gas mileage will be better or will it bite the dust cause the motor will be working harder. I also found a complete 292 good runner for 250 bucks. Is the 292 a better option then the 250? __________________ Are we there yet?

08-29-2003, 05:29 AM	#2
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,439	The 292 is a work truck engine. Very strong. Its virtues are big torque at low RPM, longevity/durability and heat tolerance. It does not turn fast. 4500 -5000 is redline for a stock 292. The 250 might run faster but I have no experience with them first hand so it would be unfair for me to venture a biased opinion. 292's are a lot of fun. I ran one in my '68 C/10 shortbed stepside with a 4 Bbl Holley, Offy intake, Clifford headers on a .030 bore from '77 to '02. I'm now in the process of finishing a rebuild of the original 292 block and I just picked up an early ('63?) 292 L6 as a parts carcass. You might ask the 250 vs 292 question at: www.inliners.org Hope this helps __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

08-29-2003, 07:15 AM	#3
MOTHERTRUCKERS Registered User Join Date: Dec 1999 Location: BRADENTON FLA Posts: 3,269	Do you know the 63 292 is the only year with a forged steel crankshaft __________________ Rest in Peace Ed. Thanks for all the good times.

08-29-2003, 09:17 AM	#4
dubie Registered User Join Date: May 2000 Location: Flin Flon, Manitoba, Canada Posts: 8,855	I used to get pretty decent mileage out of my 250 inline. ON the highway I got about 19 MPG and about 17 around town. It was backed by a 3 speed manual __________________ My name's Tim and I'm a truckaholic My 56 Chevy shop truck build http://67-72chevytrucks.com/vboard/s...d.php?t=562795

08-29-2003, 10:19 AM	#5
Brad Out of the carpool lane. Join Date: Jan 2000 Location: Clark Co, WA Posts: 5,673	At one point I could get as high as 18mpg in the truck, but that was very rare. Usually it was around 16. I haven't put any time or energy into maintanence and it's getting around 12mpg right now. The Camaro has gotten up to 25mpg on the highway! __________________ 1968 C-10 SWB, 5.7 Vortec/700R4/3.73 posi, Torch Red 1968 Camaro, 250/Powerglide, all original (No, I'm not gonna drop a 350 in it!...Jeez!) 2000 Honda VFR in the faster yellow! 2008 Husqvarna TE-610 1967 C-10 SWB 'Six Appeal'-Gone but not forgotten...

08-29-2003, 10:53 AM	#6
oldsub86 Registered User Join Date: Dec 2002 Location: Canada Posts: 695	I wouldn't say that mileage was its strong point but I have had my 292 for a long time and it has been a good motor. I used to have a 250 in a '67 shortbox stepside and I think the 292 is a much better motor. Mostly subjective I guess rather than objective as I can't tell you in detail why. I also have to admit that my 250 was about worn out and the 292 is in better condition. I like the 292 and if you want to be different, an inline is it. There is not as much aftermarket stuff readily available and the stuff that is out there will cost more. If you plan to leave it stock that will not be a problem. __________________ 1968 Chevy - 292 with a powerglide

08-29-2003, 11:01 AM	#7
truckster Senior Member Join Date: Jan 2001 Location: Orem, Utah Posts: 7,954	I have a 250 in my truck temporarily. I don't think you'd see any improvement in mileage. I get about 14. The 250 just isn't big enough for one of these trucks. It does have one interesting characteristic, though. It sounds like the old UPS truck when I accelerate. __________________ I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson

08-29-2003, 06:35 PM	#9
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	I've had several 250s. They have adequate power, but you sure won't win any races unless you spend a lot of bucks. Talked to a guy with one in a early Nova with dual Holley quads who was turning low 12's. Milage can vary, anywhere from 15 to 20 mpg, depends on a lot. My best milage was in an 80 van that had the integral head and a progressive 2 bbl carb. The 292 will give more power, lots of torque at the bottom end. I've never owned one, but do have one in the plans for my 52. I would assume that with more cubic inches, the milage will suffer some, but don't know how much. __________________ Fred There is no such thing as too much cam...just not enough engine.

08-29-2003, 07:14 PM	#10
jhwkns Registered Cruiser Join Date: May 2002 Location: Las Vegas NV Posts: 2,230	I had a 67 with a 250 in it some years back... It was a lot quicker than my dads 84 which was new at the time... but that ain't sayin' much __________________ I intend to live forever. So far, so good.

08-29-2003, 11:24 PM	#11
palallin Registered User Join Date: Jul 2002 Location: St. James, MO Posts: 1,238	My wife a 250 in her '66 Bel Air (w/ a PG). It would run on the highway all day long, but it took all morning to get up to highway speed. Mileage was poor, but I don't remember exact figures. __________________ '69 Longstep K-10: 327/SM465/T-221/Closed Knuckle Dana44/12-bolt.

08-30-2003, 07:59 AM	#12
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Most of the 6's were equipted like a farm truck.3 or 4 speeds and low rear gears.If you run an auto and maybe some decent gearing you could get decent milage.The 6's run much lower RPM's so don't expect much performance.I have a 250-3sp-3.73 and I get about 13-15 but at 65 she's pretty well wound up.I hope to swap to 3.08's and later on maybe a 700R4 or 480L. I think the uniqueness of the 6 is important if you want to drive something different from a jellybean. __________________ 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"

08-30-2003, 10:34 AM	#13
Dwaynes56&68 Registered User Join Date: Aug 2003 Location: Crawfordsville,Oregon Posts: 83	hmm, still sounds like the 6 gets better mileage then a 350. Even when mine was still in good shape it never did better then 12 mpg. Thats with 3:73 gears and 31 inch tires, auto etc. I bought the 292. The guy was selling it cheap but I tried to knock a few bucks off by commenting on the leaky front seal etc. And he was like give me a hundred and I pull it. Done deal The best part is he is letting me take all the brackets and mounts as it is coming out of a 71 truck. Anyways, the motor has a single barrel carb that looks like its seen better days. I have decided that since this motor is going in I am going to invest in a gasket kit and a exhaust and intake upgrade. I do not plan on trying to build massive power but I think a 2 barrel and a header would help. was there a factory 2 barrel intake that will bolt on? If so what truck/ car would be the place to look? __________________ Are we there yet?

08-30-2003, 11:33 AM	#14
PanelDeland I am a Referee of life. Join Date: Jun 2000 Location: Greensboro N.C. Posts: 13,993	Dwyne, as far as I know there was never a 2 bbl 6 cyl factory offering.You can visit Cliffords performance for a 4bbl intake that uses a 390CFM Holley.That upgrade will probably run around $500.00 new.For around another $250.00 you can get a header. 6cyl. performance ain't as cheap as the 'ole smallblock as you can see. If time is a factor, swap in the complete 6 and hit the swap meets for a manifold and carb. I see a guy here in the Atlanta area that carries a lot of 6 performance stuff but it may be harder to locate where you are. inlinersinternational.com is the place to ask 6 cyl performance questions.Maybe someone over ther will have some used stuff or a better deal. __________________ 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"

08-31-2003, 12:42 PM	#16
rustyold69 student wrench turner Join Date: Jan 2003 Location: wrightstown, wisconsin Posts: 192	In 1980 the straight six with the integral head had a 2 barrel carb on it and it had a dual exhaust manifold. __________________ 1969 Chevy C-10 with 250 L6 2002 GMC Sierra 2500 HD Duramax with banks six gun

09-01-2003, 04:56 AM	#17
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,439	You're right, but my head is still in the late '60s/ early '70s. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not. Last edited by '68OrangeSunshine; 09-01-2003 at 04:58 AM.



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