W
wwilkins
Guest
I have a 78 SA with the L-48 and auto tranny. It is getting about 9 mpg. Is this normal? What are some of you guys with similar cars getting?
Bill
Bill
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- 2017 Arctic White Grand Sport
77 with the same config gets 11 - 12 around town. I could get 9 if I wanted to
.
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7
78SilvAnniv
Guest
Only 9!
:eek
I really think 9mpg (esp. at European prices!) is awful. You need to get that L48 to breathe better, because something is wasting a lot of your fuel. I don't know what the problem is, but I know I had double your mileage per gallon.
My 78SA, L48 automatic, stock, would get about 18-20mpg, at the last of it's life!
(the 4-5 years I drove it before the engine died and was swapped)
Have since put in a GM crate engine, still retained the same gas mileage of 18mpg...UNTIL...the chambered exhaust.
I think the chambered exhaust sucks the gas right out of the heads. Or it could just be that I like the sound of the exhaust so much, I put my foot in her more just to listen to her roar!
Heidi
:eek
I really think 9mpg (esp. at European prices!) is awful. You need to get that L48 to breathe better, because something is wasting a lot of your fuel. I don't know what the problem is, but I know I had double your mileage per gallon.
My 78SA, L48 automatic, stock, would get about 18-20mpg, at the last of it's life!
(the 4-5 years I drove it before the engine died and was swapped)
Have since put in a GM crate engine, still retained the same gas mileage of 18mpg...UNTIL...the chambered exhaust.
I think the chambered exhaust sucks the gas right out of the heads. Or it could just be that I like the sound of the exhaust so much, I put my foot in her more just to listen to her roar!
Heidi
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- #4
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wwilkins
Guest
Fortunately I can buy my fuel tax free, compliments of the US Air Force. We only pay about 2 bucks per gallon. Off base in England it's around $5.20 per gallon. My car runs a little rich. Well I guess if I get half of Heidi's mileage it's a lot rich. Thanks for the answers. Now I need to find my vacuum gauge and fix my carb.
Bill
Bill
Stallion
Well-known member
Also, if it is your carb and it is leaking, then I would be careful. C3s are notorious for catching fire and a recent thread with a reply by JohnZ (he knows what he's talking about 
) he says that it's usually the carb that's the problem.
Good luck!!
TR
) he says that it's usually the carb that's the problem.Good luck!!
TR
MaineShark
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wwilkins said:
:eek That's way, way, way low. Last fill-up was 17.48 gallons, 287 miles --> 16.4 miles per gallon. And that's an L-82 with an auto tranny. And that's with me putting my foot into the carb on quite a few occasions. Your L-48 should definitely be getting better mileage than that.
When I first got the car, I was only getting 15 miles per gallon. A tune-up (including checking, and repairing, the distributor's advance system) gave the extra 1.4 miles per gallon.
Joe
M&W's72vette
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I have a 72 with a 427/4 speed, 3.08 gears and I get 14 mpg crusin at 75 mph. Is that good??
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TomOB
Guest
Alot of people talk about the 700r-4 nearly doubling their mileage into the mid twenties. Maybe it all has to do with that missing 4th on the autos.
Im waiting on a potential 4spd, so i have no idea what mileage to expect, any ideas?
Gte the car tuned liek maine said, and check the carb. Are these city or highway type miles, and is your right foot full of lead?
This info woudl probaly help others whoa re more knowledgeable tell you how far out of raneg you really are and also help me know what to expect.
tom
Im waiting on a potential 4spd, so i have no idea what mileage to expect, any ideas?
Gte the car tuned liek maine said, and check the carb. Are these city or highway type miles, and is your right foot full of lead?
This info woudl probaly help others whoa re more knowledgeable tell you how far out of raneg you really are and also help me know what to expect.
tom
MaineShark
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Stallion said:
If the timing is not correct, more fuel is required to run properly. In other words, the engine is less efficient with improper timing, so adjusting the timing allows it to operate properly on less fuel.
Joe
Stallion
Well-known member
Okay, I understand what you mean, Joe.
"Im waiting on a potential 4spd, so i have no idea what mileage to expect, any ideas?"
All depends. What year? Small block? Big block? What exactly are you looking at? This ranges from year to year in the shark.
"Im waiting on a potential 4spd, so i have no idea what mileage to expect, any ideas?"
All depends. What year? Small block? Big block? What exactly are you looking at? This ranges from year to year in the shark.
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TomOB
Guest
i assumed we were rfefering to an L48, specifically an 1980 one.
JHL
Senior Member
Hi
My 81 probably only does about 10-12 mpg on the open road and less around town, the last one I had was an 80 L48 4 speed and when I first purchased it, it was completely unmodified. I measured the fuel consupmtion once on a round trip from Edinburgh to London and it averaged a shade over 17mpg so I would expect and automatic to be slightly worse.
J.
My 81 probably only does about 10-12 mpg on the open road and less around town, the last one I had was an 80 L48 4 speed and when I first purchased it, it was completely unmodified. I measured the fuel consupmtion once on a round trip from Edinburgh to London and it averaged a shade over 17mpg so I would expect and automatic to be slightly worse.
J.
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wwilkins
Guest
I stood there with my air cleaner off and watched fuel flowing from inbetween the top plate and body of the carb. So off comes the carb and when I got it apart I had bent one of the needle valves on the power piston. I really hate it when I am the bubba. So a c note and some humble pie later I had a vette shop over here put it back together for me with some new parts. I don't know about mileage yet but I was on it pretty hard today and no smoke and boy did it accelerate.
Bill
Bill
81 Corvette
Well-known member
I have since added a Flex-a-lite dual 12 in fan set up and it seems to have added about 1/2 mpg
here is my data:
Total Miles 6,352 Total Operating Days 245
Total Gallons 556.4 Miles per Day 25.9 Miles Per Month 789 Miles Per Year 9,463
Average MPG 11.42 Gallons Per Day 2.3 Gallons Per Month 69.1 Gallons per Year 829
Total Fuel Cost $847.17 Fuel Cost Per Day $3.46 Monthly Fuel $105.18 Yearly Fuel $1,262
Avg. Fuel Cost $1.523
here is my data:
Total Miles 6,352 Total Operating Days 245
Total Gallons 556.4 Miles per Day 25.9 Miles Per Month 789 Miles Per Year 9,463
Average MPG 11.42 Gallons Per Day 2.3 Gallons Per Month 69.1 Gallons per Year 829
Total Fuel Cost $847.17 Fuel Cost Per Day $3.46 Monthly Fuel $105.18 Yearly Fuel $1,262
Avg. Fuel Cost $1.523
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B
BORDERBUM
Guest
I would agree with the poor 9 mpg statement, for the l48, my 77L48 probably gets the same. I would rebuild and go for more power, new carb and intake! You then would get better mpg than you do now and have plent more hp!! Those motors were terrible for power and mph in the late 70s. I think my 77 came stock with 160 HP!!! When I got her from a Corvette GooRoo, He had preserved it as an all original car babied it and took real good care of her( Until the garrage door fell off on her front end, couldn't take the originality mess up and sold her) Anyway I could not even peel out with the car!! I put a shift kit in by B&M and still could not peel out in the car.
hopes this gives you a little info on your late 70s generation Power Robbing ERA Vette. Just my $.02
GIT R DONE__________________BORDERBUM
hopes this gives you a little info on your late 70s generation Power Robbing ERA Vette. Just my $.02
GIT R DONE__________________BORDERBUM
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resto75
Guest
Boy 81 you do really keep track of your gas mileage.
I get about 13.8 miles to the gallon on the 75 in normal driving. With my 750 vac secondary Holley carb. I have heard that if you go to a performer carb you will get better mileage. Has anyone else heard this about the carbs ??
I get about 13.8 miles to the gallon on the 75 in normal driving. With my 750 vac secondary Holley carb. I have heard that if you go to a performer carb you will get better mileage. Has anyone else heard this about the carbs ??
81 Corvette
Well-known member
resto75 said:
Every fuel purchase goes into an Excel spread sheet. Doing 75 on the freeway equals 18 mpg. Lots of puttering in the city nets 9-10. I'm a dork, but what can you do.
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A
AUSSIEVETTEMAN
Guest
Fuel usage
Bill
My 81 Coupe gets around 9 miles to the gallon as well around town.
I topped her up the other day and she had done around seventy miles for about 28 litres ($21 Aussie Dollars and around 7.5 US gallons)
She doesn't have a stock carby on her, she has a Holley 650 double pumper. She seams to idle sooty, leaving soot marks on the driveway and I think that the 650 CFM carby is restricting top end performance as the original Rochester is 795 CFM.
As the boys said in the latest edition of Vette mag, the more air in, the more power out.
Cheers
Bill
My 81 Coupe gets around 9 miles to the gallon as well around town.
I topped her up the other day and she had done around seventy miles for about 28 litres ($21 Aussie Dollars and around 7.5 US gallons)
She doesn't have a stock carby on her, she has a Holley 650 double pumper. She seams to idle sooty, leaving soot marks on the driveway and I think that the 650 CFM carby is restricting top end performance as the original Rochester is 795 CFM.
As the boys said in the latest edition of Vette mag, the more air in, the more power out.
Cheers
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