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-   C3 General (https://www.corvetteforum.com/forums/c3-general-119/)
-   -   Hwy driving (https://www.corvetteforum.com/forums/c3-general/3210841-hwy-driving.html)

redwhitekat 02-01-2013 02:11 PM

I don't mind the short trips but if you wanna take it for a nice weekend getaway forget it. I wanted to go from toronto to Chicago in June for the drag races at the old airport and I can't imagine driving 10 hours lol but ill still prob do it haha

John 65 02-01-2013 03:03 PM


Originally Posted by 80Baby (Post 1583006424)
Speaking of 5-speed, I'm surprised those guys haven't chimed in on this thread yet. I sold the 4-speed out of my '80; I'm putting in a 5-banger for noise and mileage. There's that old adage "If you can't afford the gas, then you can't afford a Corvette." I don't necessarily agree. The oil companies are gouging us and I simply hate giving them my money. That's why I suck it up and drive a Toyota Yaris to work everyday. It's all about the principle. :D So a 5-speed in the Corvette is a must for me.

:iagree: Me too. 4th is fun in these old toys for all the above reasons for sure, but on a long trip down the highway, for me, ya just cant beat 5th gear. Its a joy.

flyeri 02-01-2013 04:27 PM

I did not enjoy the car on the highway with the loud side pipes. About an hour of it and I was through. I swapped the 4spd for a 5spd and it made all the difference in the world. Mileage is greatly improved and noise level on the highway is way down.

qwank 02-01-2013 04:53 PM

My '81 with the Richmond 5 speed 2.87 rear gears is at 3000 rpm at 85. now problems here, I love driving on the highway. Should be even better this summer with my rebuilt suspension and new wheels and tires.

ddanis60 02-01-2013 05:32 PM


Originally Posted by Easy Mike (Post 1583005362)
Is the computer still on your 81?

When tuned, I could get 18 highway out of my 74 L-48. I could get 16-17 out of my 80 L-82.

If you can get no more than 12 out of your car, it's time to find out why.

:thumbs:

Yeah its still got the factory computer. seems like the factory quadrajet as well. very fumey when idling and ive smelled gas once this week while idling. im sure it needs tuned, as the guy/co worker i bought it from did zero maintenance and never drove it for 7 years. i changed the oil last week first thing. seems to shift perfect, but when warm, idles near 500. yeah i was just surprised that in the 100 miles i drove to get the calculation, i was averaging 12. that is with 2 ginormous hills on the way to work, and also some slightly spirited driving around town. nothing crazy though. the first 100 miles isnt quiet enough to get a valid mpg estimate either i dont think. runs and drives smooth as butter. loud though.



Originally Posted by gbvette62 (Post 1583005488)
Something doesn't sound right with your 81. Unless the rear gears have been changed out, it should have a 2:87 rear. With those gears, I'm thinking you should be in the low 2,000 RPM range at 70?

The EPA combined mileage for the 81 Corvette was 14 for the 4 speed and 15 for the auto. The highway rating was 22 for the 4 speed and 21 for the auto. In normal driving, I use to get around 14-15 with my 81 automatic, and though it's been a long time since I took it for an extended run down a highway, I'm pretty sure it use to get me between 19 and 20 at a 70 MPH cruise.

I can see where 12 MPG could be possible under really hard driving, or in stop and go traffic, but it seems a little low for normal driving conditions. If that 12 MPG was on the highway, I'd have to say that something is way out of whack!

I have the auto. 3 speed, and strange not having an overdrive. i dont mind the high rpm, but just weird getting used to it again. at 70-75 or so, im around 3k. the car runs great, but mileage and fumes (has no cats, but worse than i think it should be even considering the exhaust) make me think the carb needs to be looked at. Ill replace the plugs and air filter this week. anything else i should take a look at?

scorpion18z 02-01-2013 05:37 PM


Originally Posted by ddanis60 (Post 1583004979)
I just got my 81 last week. It has a few small mods, but i wasn't feeling all comfortable about being over 3k on the highway. i also calculated gas mileage for the first time yesterday, and when i saw an average of 12.. i wasn't pleased because i figured something was wrong. After seeing this thread.. i guess things are pretty much normal, ha! I havent been at that high of rpm since i had my 5 speed cobra with 4:10's at 80mph.

I guess after getting out of my z that gets 26 on the highway, it was just a shock. Is there anything in particular that could slightly boost mileage on my L81? Its got headers and cat-less exhaust.

-Dave

Sell the Vette and by a Hybrid, otherwise forget about gas economy; it takes a lot of gas to make power. Hell look at how much it takes to get a rocket in orbit. We are lucky with our rockets.

ddanis60 02-01-2013 06:02 PM


Originally Posted by scorpion18z (Post 1583008634)
Sell the Vette and by a Hybrid, otherwise forget about gas economy; it takes a lot of gas to make power. Hell look at how much it takes to get a rocket in orbit. We are lucky with our rockets.

Takes a lot of gas to make power? I also have a z06 and it gets nearly 30 on the highway.. and has over 500 hp. Just saying. yeah yeah.. it also sits at 1500 rpms when cruising, lol. thank you modern tranny's :) While i dont flog my z everywhere i go, i get easily 18 to 23 combined and i always have a heavy right foot when i drive that car. I also have a 90's civic that honestly doesn't have much less power than the L81 (sad to say) and it gets 4 times the mileage.. almost.

I love my c3. 1981 not the most desirable of the 3's, but i got it cheap and ive always wanted a 3rd gen. I'd drive it if it got 5 mpg. It's a 4th vehicle and is purely fun. plus it gets 10 times the compliments of its younger brother the z.

Funny you bring up rockets.. I work on large guided missiles for the air force and yeah, blasting off an icbm into space is def... powerful and loud. Wouldn't mind that kind of power. Please know all of this was in fun and good convo. I dont want to seem like a smartazz. :cheers:

~Stingray 02-01-2013 06:11 PM

I don't hate it. But I prefer city driving so I can shift through the gears and not just hold a gas peddle in place.

Torqued Off 02-01-2013 06:36 PM

How about you just slow down and drive responsibly at the published speeds, that are both safe and avoid killing someone.

Street Rat 02-01-2013 06:47 PM


Originally Posted by redwhitekat (Post 1583004030)
Anyone like me hate driving on the hwy with your vette I find on my 74 4 spd if you are going 70 80 miles an hour the rpms are just so high for a v8 and car is Loud cause of the high rpms and mufflers that its just uncomfortable plus gas mileage is down the drain with those rpms so high

Sounds like it's time for you to buy another transmission with overdrive.

gbvette62 02-01-2013 07:12 PM


Originally Posted by ddanis60 (Post 1583008581)
I have the auto. 3 speed, and strange not having an overdrive. i dont mind the high rpm, but just weird getting used to it again. at 70-75 or so, im around 3k. the car runs great, but mileage and fumes (has no cats, but worse than i think it should be even considering the exhaust) make me think the carb needs to be looked at. Ill replace the plugs and air filter this week. anything else i should take a look at?

81 was the last year with a 3 speed automatic, 82 went to the overdrive. The 81 did have a lock up torque converter, in an effort to help the gas mileage.

Throw in some new plugs, and maybe even some new plug wires. Check the timing, and also all of the vacuum lines. If your getting a lot of fuel fumes, is there any sign that the carb may be leaking. It's also possible that the car is running rich, would could explain the fumes and the poor mileage. It couldn't hurt to pull the carb and go over it, or even replace it.

Manuel Azevedo 02-01-2013 07:27 PM

Don't know what maybe wrong with some of the cars here, but my 68 with chambered exhaust gets 18 on the freeway and just sings to me down the road!!

Redwing01 02-01-2013 07:28 PM

Nothing better than hitting the open road , roofs popped and enjoying the hell out of my C3.
I've never paid any attention to gas mileage as I maybe drive it once or twice a week , when its low I fill it!

scorpion18z 02-01-2013 09:56 PM

LOL! "When it's low, I just fill it back up again."

My other car is a 30 year old el Camino (which I have had since day one) and I don't remember getting over 15mpg at any period of its life. Funny thing is that I just rebuilt the carb last week with a new gasket and accelerator pump, new fuel pump, plugs, distributor cap & rotor, fuel & air filters, oil and filter and now get 12mpg. WTF??

I do like the new technologies introduced in the C7 (and any new car for that matter) and enjoy reading about how they control the internal combustion engine and, it seems, they have it figured out until the next version, but my tools are too old and my head is to full of "good ole day" techniques to be in the same class as the systems control computer. I still marvel at grabbing a hold of the dizzy and turning it left and right to find the sweet spot or looking at a part and being able to pronounce its name.

This is a fun thread and, I too mean no harm, just having fun BSing with the FGs and talking cars.

Dustup7T2 02-01-2013 10:15 PM

I assembled mine to run with the big dogs at interstate speeds on a regular basis. I wanted a cruiser and not necessarily, a garage queen. Not a racer either. I wanted to have some range with the factory capacity tank.

I wanted sidepipes. And music. And a heater. And windshield wipers. When I go to lower altitudes, having AC would be daytime nice so that's on the bucket list but it's not a show-stopper without it.

It won't earn Top Flight status, for now but that's fine too. Meanwhile, I am driving the wheels off this mule and racked up over 30K relatively stable miles since May 2010.

It's not a DD but as long as the roads are dry, I'm burning fuel at a rate of 20.5 mpg as pictured and loving that OD...

http://i259.photobucket.com/albums/h...psc23cdbcc.jpg

BTW, in town, 1st through 4th, can be "spirited" driving too. :D

U17 02-01-2013 10:44 PM

383,3:08,Hooker headers and sidepipes....700R4.. and ear plugs (for wind buffeting)....if wanted...tops never on also.... 1975 rpm at 70..Signed up for 2013 Power Tour,Long Haul ...

qwank 02-02-2013 08:22 AM

when I had the 3 speed auto in my '81 I was averaging 18mpg

alswagg 02-02-2013 09:29 AM

When I had a quadrajet on the car, running 65mph. We averaged 20 mpg, with the Holley, we averaged 18 mpg. By the seat of the pants feel. The Holley seemed to be more responsive and quicker than the Qjet. The Holley evens seems a little lean while cruising. I feel the Q jet was spot on. I suspect the accelleration of the holley is why we get lower milage. Oh, I run the timing at 36* advance at 3,000 rpm. Al

C3 4ME 02-02-2013 09:52 AM

79 L-82 4spd, 3.70 rear. The best I've done ont he highway is 15.8 MPG. Even with headers and flowmaster 50s, I don't think it's too bad. With the tops off, there's more wind noise than anything. With the tops on and windows up, the rattling hurst shifter is louder than anything.

71scgc 02-02-2013 09:53 AM

You must be young. Time was, all cars ran revs like this on the highway.
Get a 5-speed. I did. If you like the noise, leave it in 4th. If not, use the OD.
BTW gq's car is steel cities grey. A very nice SCG. Don't think you could ever get a better looking SCG than he did. My car and myself are envious.
Someday...
Carter


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