Here's the thing. I'we recently came across TBI 350 SBC engine. as in a matter of fact. I don't know anything about the engine aside from that it came out of a Suburban.
My plans are to put this engine into a CJ-5 Jeep that's on 38" Mudder tire's and I am going to use this Jeep mostly for trip's, highway and off-road. Because of where I live I need to drive on the highway for hours just to get to play in snow/sand whatever. So basically I need to get as good gas mileage as possible.
The Jeep itself is around 3500 lbs. and as mentioned above is on 38" tires and I will be using TH-350 Transmission with stock converter. The Jeep has 4.10:1 gears in the Dana axles.

Are there any modifications i could do to the engine, to get the gas mileage as low as possible ?
The engine is as above mentioned a Bone stock 350 TBI from the Suburban truck. I am going to run exhaust manifolds that hopefully will run into dual 2.1/2" exhaust (or what do you recommend) ?

I had thoughts about running an Aluminium intake manifold with good Quadrajet over the stock TBI system. and then i would change the ignition to GM-Hei. would you recommend running an MSD ignition box with the HEI for improved spark and durability ? what do you say about that.

If I'm not clear on some things, Please ask.
The bottom line is I need as good mileage as i can get along with low end torque and reliability.

Here are two picture's so you can get a picture of what the jeep would mostly be used to. (the muddy picture is just there for fun, this is not heavy mud as you can see, just basically a dirty water)

http://icejeep.com/album/albums/ymsar_myndir/Bergur/B%F3i/normal_177.jpg
http://icejeep.com/album/albums/ymsar_myndir/Bergur/B%F3i/normal_247.jpg

Greetings from Iceland.
Take care.

Greeting from Petaluma California.

First of all that engine is over 20 years old; with that said it's a very popular conversion.

2. I'll take tbi over the quadrajunk any day, although it used to be one of my favorite carbs. You will need a different intake manifold for the quadrajunk and will have to do some modification to the manifold to make it fit. A Hei distributor is more then adequate.

3. The cj-5 frame is a little light for a v-8, as are the stock axles etc. And plan on something to counter axle wrap.

4. There is a lot of good stuff at this site, check the jeep FAQ bible, and use the search function or google, as I mention earlier this is a very popular conversion, you should be able to find a ton of pictures and info to help you along.

5. Have fun with your build, because nothing sound as good as a healthy v-8!!

I'we no worries about the Dana 44 axles, The last engine I ran in this Jeep was a 500+ HP 396 BBC, so the Jeep frame is just good enough for what I'm doing. The engine before that was an earlier 350 Sbc. But since all that I'm concerned about with this engine is to get as good gas mileage as possible. I thought it would be a good idea to ask you fellow Jeepers, what would be best to do in this situation, as the only concern here is to get decent mileage along with acceptable low end power.
I wan't to use the swirl port Tbi heads because not only they have 64cc chambers for decent compression they also have 1.94"/1.5" valves and though they run out of steam at 4500 rpm that's just OK for what I'm doing right now. I also heard they deliver good fuel mileage, which is another BIG plus for my application.

So Before I do anything I would like to discuss it a little here, I now about the search button and all that, and believe me I'we tried to search, but as they say "every application is different,, I thought It would give me the best result just to ask them experienced Jeepers.

Also one thing to consider... That's what would be realistic gas mileage for a Jeep like mine on the interstate 50 Mp/h limit. some say I would be lucky to get 15 Mpg... Also considering what would be acceptable vacuum for the engine, when running at 50 Mp/h on the highway ? I'm assuming as high as possible :) but what would be realistic for an original cammed Small Block Chevy that's driven 60.000 miles ?

And what could I do to get the best fuel mileage possible without tearing the whole engine apart !!!

Thanks.
Kristjan...

Anyone ?

I run the same engine. I took all the smog stuff of and tried an Edelbrock intake w/ an adapter w/ the throttle body. I did not see a difference. The biggest thing I see, is it runs rich as hell. I have the O2 sensor, MAP etc, but it will still make you cry if you stand behind it. I run a 700R4 for the overdrive and that helps on the gas mileage a little. I did have to get an adapter to run my Dana 300. Not many mods you can do for better gas consumption. It is a Jeep. I run 39s w/ one tons and have 5.13 gears. Mine is primarily a trail vehicle, but does makes trips to 7-11, icecream store and the parts store from time to time. I love the TBI for the off camber stuff. I used to run a carb, but the fuel inj 4 cyl rides would toast me on the trail. Couldn't have that. Drive it and enjoy it. If it was a daily driver, I would suggest a Vortec 4.3 or the like. It has almost the same horsepower, a little lighter and somewhat better gas mileage.

Thank's for the answer :D