I have a 65' CJ5 with the 134 sewing machine motor. lol I am actually going to challenge myself on this project. I am wanting to know if there is anyway I could get gas mileage out of my current engine. I am wanting to us it as a work driver and weekend warrior of course. I want some gas mileage though. I thought about starting with a newer 2.5 but they dont get any mileage stock either. lemme know if anybody has any suggestions. thanks

unfortunately, there is no jeep that gets great gas mileage.
The newer efi's do somewhat better but you're still pushing a brick down the road.

You want it all don't ya? Did ya ever notice what vehicles it is that gets milage? Well Jeeps ain't one of them is they?
Kidding aside, for gas milage maybe a Yamaha 90 for around town would be about the best you could do.. Then you could drive your Jeep offroad..
The best milage I ever had was in overpowered vehicles.. A 96 SS Caprice did me real good on the hiway. I also pulled the engine out of a new 86 chevy 1/2 ton and replaced it with a home built 400 cu in.. That truck got me 17/18 on the hiway back in 87.
I've never had much luck with little engines getting me milage. Always seemed to be straining to go faster..it seemed.
I don't know how on earth you could get much more than 10/11 mpg with that jeep no matter what tricks you think you can do to it..
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

figured i'd get some jokes. thanks for the replies tho. i think i am going with a chrysler slant 6 as usual, for gas mileage and dependablity you cant beat em. gotta figure out the tailshaft/transfer case and i think i have that swap figured out. My dad put a slant 6 in a cj-8 and got 23 mpg! thats what i'm talkin about.

Jim is on point here, overpower does seem to be the best route especially if your vehicle has disadvantages to start with. I had a '78 Chevy 3/4 ton 4X4 Suburban that originally came with a 350. All it was capable of was around 11 or 12 mpg at best on the highway. 2 years later, I dropped a bored out 400 sm block in it and the mileage jumped to almost 15 mpg. The more horsepower it seemed helped push the 5800 lbs down the road with less effort, hence less fuel consumption. As for a small vehicle like a CJ tho, I dont know where the point of diminishing return would be. I have heard that all the engines (4, 6, and 8) are pretty close in mileage ratings. You just cant escape that flat faced front end! Altho you have a 4 cylinder, the gearing installed to apply the power to the wheels prevents the mileage benefit. About the only way you can realize any more mileage with your set up would be to find an overdrive unit to use while cruising at highway speeds. If you plan to put bigger tires on, forget that, you will be constantly shifting out to climb hills. Jeeps are not designed to be fuel efficient, they are designed to be fun! Since the EPA got involved, they have started to try to do something about the problem. Thats why you see EFI's, 5 speeds and more aerodynamic shaping in the newer models. <img src="/forums/images/graemlins/notooth.gif" alt="" />

Pulled this off of wikipedia for all you nerds like me!

http://en.wikipedia.org/wiki/Air_resistance


Josh

I would encourage you to restore the whole Jeep, including the F-head 134 huricane engine. Are you certain it's a CJ-5 and not the CJ-3B? Both were available in 1965.

I think you should take your dad down to the police station and hook him up to one of their machines..then ask him that question again..
There ain't no way in hell that combination would get that much milage!
The first thing to check is what the gear ratio is in them axles. Then compute what rpm your engine would be running at.. I'm thinking that Jeep has 5:40's in it or somewhere close. The bigger engine you put in front of them low gears the more gasoline it will take to spin it up.
Milage occurs from preformance at low rpm..period!
Put 300 horses in there and some 2:70's and you might get 20 or so.. But off road you would have a sled..
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

my bad i didnt write in the details of the swap. and i got a little bit wrong. I haven't asked him yet but I believe it was actually a CJ-6 2wd 225 slant 6,904 tranny,3.73 gears. it had a bunch of dodge pickup stuff on it so probably the dodge rearend. but he swears up and down it got steady 20+mpg back and forth to work @ 55-60mph.

well, great question. I don't know very much about the vintage jeeps but, all I know is, It is a '65 has a 4 cylinder that sounds like a singer sewing machine. Hard top with no rollbar. pto winch seems factory. It has a Kaiser tag on it as well.. What's the difference between the two?