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Expected gas mileage for CJ-7 i258???

6530 Views 10 Replies 3 Participants Last post by  **DONOTDELETE**
I have an '82 CJ-7 with a tired i258 straight 6. I currently get about 10-11 mpg. I am planning to swap a rebuilt 258 in. I was wondering what the average gass milage for a rebuilt 258 should be. Everything is pretty much stock including my T-5 tranny. I am running 31X10.5 BFG Mud Terrains. This is my daily driver, so gas mileage is fairly important. Thanks in advance.


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You probably wont get much better mileage. Carburation, tires, drivetrain and driving habits all affect MPG. I have a 85 CJ8 with a rebuilt 258, newly installed Weber carb and 35 x 12.5 tires. I got slightly better gas mileage, maybe as good as 13 MPG or so. Marginal at best. If this Jeep isnt your daily driver then (IMHO).... who cares? As long as it runs well and makes you happy, then go with it.

85 CJ8,258,Weber32/36,4" BDS lift,4.10,35"tires,f/r lockers
My 82 CJ7 with 258, hardtop, 31X11.50X15 tires and auto. transmission got 15mph on the highway. I had another one like it only with 304 V8 and auto and it got about 12 or 13mpg on the highway.

I have an 85 CJ-7 w/258, T5, 30X9.5 and i think 3.31 gears.
I get an average of 17 mpg or so, and the engine has over 137,000 miles on it.


Patrick Kulas
85 CJ-7
Just a thought ......were the 31's stock on that beast? So ..... I'm wondering if you're actually covering more ground that you think.......hence better than 10-11. My mostly stock TJ gets between 16-17 ......but I'm still hoping to squeeze it to 20 (a man can still dream can't he?).


i have a 87 wrangler with a engin that is completly shot and i get 12mpg......and i hope to get better gas when i replace it!

I have an 84 CJ7 with a 258 and 118k miles, T4, HEI, and a stubborn Carter BBD and I get 19 mpg highway and 13 in city. I don't hear too many 258s getting any better than this, even after rebuilds.
I have an old advertisement I found in a magazine for a 81 Laredo and it advertises 26mpg highway and 22 in the city -
this must have been the GM four banger with a T-5 cause I have never known a jeep with that kind of economy.
Just Empty Every Pocket


My 83 CJ-7 (258,4spd) with BF Goodrich AT 31's and aluminum rims just got 13.8 mpg. Another CJ I had (258,5spd) with a hard top got 14-16mpg. My wagoneer got about 9mpg

When I had a 258 in my Scrambler (I now have a 304), I was running 32 BFG's and had a T-5 tranny. I was getting 13-15 mpg . . . that is, when I kept my foot out of it.

Keep on Jeepin'
I run a '86 CJ7 with over 100,000 on the odometer, 31X10.50 15's and get about 18-20 on the road. I use a Weber that took me forever to tune because of my mistakes and a borla exhaust, thats about it.

Back when I first got my CJ7 and the computer control system was workinng right I decided to check the mileage on a road trip through the Mojave. I got 19.9 MPG. I had a 258. T-5, 3.31 gears and 33" BFG ATs at the time.

When going from Mn to the Rubicon a couple of years later I got about 18 MPG across Mn, Iowa, and the first half of Nebraska, but then my mileage started to drop as elevation went up. I ended up at around 10 to 12 from Wyoming to Tahoe due to the elevation and all the hills. The Jeep was very heavily loaded on this trip.

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