Miles per gallon???????
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Hwy steady 60, 18 is about right, with overdrive auto 22-24 is more like it, assuming you have a really good tune, if you had DPFI on it, that would be the same figger at 90mph cruise....
around town/mixed bag figger on 12-15 mpg, depending on your foot....
Old club member years ago complained of only 6-8 mpg in his 435 horse BB.....
the club just roared with laughter saying that IF he EVER took his toes outta the freeking CARBS maybe he could get a bit better......he had tripower on it....he drove it like a deranged animal....
around town/mixed bag figger on 12-15 mpg, depending on your foot....
Old club member years ago complained of only 6-8 mpg in his 435 horse BB.....
the club just roared with laughter saying that IF he EVER took his toes outta the freeking CARBS maybe he could get a bit better......he had tripower on it....he drove it like a deranged animal....
Le Mans Master
Joined: Oct 2007
Posts: 7,445
Likes: 971
From: Tennessee/Rhode Island
In my original owners manual for my 4 speed, not auto, the original owner logged his miles per gallon starting from August 10, 1978 through September 17, 1978 (the car was built in October 1977). The exact miles on the car is unknown at that time but probably quite low and the type of driving done in Northern New Jersey where he lived in probably mixed city/Highway. Here are the following entries, MPG: 18.95, 14.70, 17.2, 18.1 17.6, 16.1, and 16.2. Pretty cool!
Instructor
Joined: Feb 2006
Posts: 200
Likes: 0
From: Whitmore Lake MI
Mpg
When I first bought my 78' it got 8-10.
When I dismantled the L-48 I found very thick carbon crud on top of every pistion! Always ran rich, and it showed. I'm hoping the rebuild,
proper tuning and a properly working vacuum advance (that wasn't working either I found) will get me back in the ballpark of 15-18.
When I dismantled the L-48 I found very thick carbon crud on top of every pistion! Always ran rich, and it showed. I'm hoping the rebuild,
proper tuning and a properly working vacuum advance (that wasn't working either I found) will get me back in the ballpark of 15-18.
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Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
I purchased a 1977 Corvette new back in the day. We took it on a number of trips back then and checked the mileage dutifully... some may recall how important gas mileage became back then with gas lines at times. The best I was able to get (fully loaded L-48/auto and the A/C on) was 21 mpg... definitely not bad for the times. Around town mileage was typically 15-16.
My '73 with L-82/4-speed and 3.36:1 gears gets 14-15 around town. Haven't taken a trip in it in 18 years...
Good luck... GUSTO
My '73 with L-82/4-speed and 3.36:1 gears gets 14-15 around town. Haven't taken a trip in it in 18 years...
Good luck... GUSTO
Intermediate
Joined: Oct 2008
Posts: 37
Likes: 0
From: toronto ontario
i don't know because my speedo is not working (broken trans drive and or driven gear) but its around 11.6-16 mpg(20-14.7 L/100km) and its stock 3.08diff 3speed auto with dual 2.5" pipes
an ls1 conversion looks pretty good.
alot depends on foot.
an ls1 conversion looks pretty good.
alot depends on foot.
Thread Starter
Advanced
Joined: Dec 2008
Posts: 71
Likes: 0
From: California
3rd Gear
Joined: Mar 2008
Posts: 3
Likes: 0
You are all pretty lucky. I am getting 9 - 11 mpg but a good thing there is always a gas station nearby. I am going to get the engine rebuilt and hope that adds 6 - 9 mpg. In the end it is a toy and toys never come cheap 
Drifting
Joined: Jun 2004
Posts: 1,881
Likes: 9
From: staten island ny
In my original owners manual for my 4 speed, not auto, the original owner logged his miles per gallon starting from August 10, 1978 through September 17, 1978 (the car was built in October 1977). The exact miles on the car is unknown at that time but probably quite low and the type of driving done in Northern New Jersey where he lived in probably mixed city/Highway. Here are the following entries, MPG: 18.95, 14.70, 17.2, 18.1 17.6, 16.1, and 16.2. Pretty cool!
ESU
Drifting
Joined: Feb 2005
Posts: 1,738
Likes: 2
From: San diego ca
The best I ever got in my 78 with the 4 spd was 20 mpg on an entire freeway trip.. i.e. fill up along side freeway - drive freeway till next fill up...this was on my way to the 50th anniv. at the Monterey historics... Since then I have swapped in the tremec TKO overdrive 5 spd.. i can now get 24 on the freeway under the same conditions.
City driving with the 4 spd was low 13-14 tops.. it isnt much different with the OD in the city.
City driving with the 4 spd was low 13-14 tops.. it isnt much different with the OD in the city.
