[78CJFIVE]

Hello from sunny Mosul, Iraq! I'm at a crossroads with my CJ. Here's the situation:

It needs a lot of work, and for the most part I intend on doing this Jeep right the first time. I plan on keeping it for quite some time. It won't be a daily driver, but I would like it to be street legal, highway capable, and dependable. Able to be a daily driver if I wanted to use it for that purpose.

I'm in the Army, currently deployed to Iraq. I've had the '78 for about a year now, but have not done much to it at all. Now, I don't have a huge budget, but I will have some money to spend when I return home. It needs body work and paint, and I will need to pay to have that done.

Okay so without making this 1000 words.. I am trying to decide whether or not I should keep my 258 or drop in a v8. I want fuel injection eventually. I want to be able to run up to a 35, but I probably won't ever go that high. My 258 needs rings and it's a little tired.

I guess what I really want to know are the limits and capabilities of the 258. I know it can be a strong engine, but how much work is involved. About how much would I expect to pay to fuel inject it? Should I do the head swap? Junkyard fuel injection vs a kit? Would it be better to just find something like a Ford 302 that's already injected? Would like some guesstimates of cost of keeping it vs swapping. Just looking for some advice. I want to start planning for this build when I get home and searching for a swap now if that's what I decide.

Thanks for helping another indecisive jeep owner. =)

[hole]

I would rebuild the 258 and install fuel injection. Mine has the Mopar kit on it, Huge differance! The Mopar kit is $2500-2800 . Howell makes one too and I believe its $1500-1800. The 258 will turn 35's if you change the diff gears.

[Sfisher]

I have the 258 with 4.0 head and Mopar kit on my Scrambler now. In my opinion, after doing two swaps on my first CJ7's (one a 350 TBI and second a 4.3 Vortec) the MPI kit was much much easier. I wheel with 35's and 4.56's and I am able to use 5th gear on the freeway with no problem.

I'm just a shade tree mechanic who likes to tinker so if you have more skills then maybe you would want the V8 and it would come easier for you. I do mostly crawling in mine and the 258 has plenty of power for that. If I was doing more sand or mud wheeling then I'd be more inclined for the V8. But as it sat with the 258 I am very happy with my choice.

Lastly, and most importantly, thank you for your service sir. We owe a world of gratitude.

[78CJFIVE]

Right now I am leaning towards keeping the 258.

About what should I expect to pay for a master rebuild and head swap? I won't be doing the work, beside pulling it and taking it to the shop. I've never rebuilt engines.

What other improvements for the 258 should I look into? I don't think the FI kit would fit into my budget, so I would probably go with the junkyard TBI with the 4.0 head when I do decide to inject it. I guess if I kept the 258 i would have some time to gather up the parts, or just keep it carbed for now, and do the FI sometime down the road. Any reason why I would want to do it while the engine is out of the Jeep?

I just want to be sure that I'm not going to want that v8 down the road somewhere. My 258 is far from dieing, I could keep it alive for awhile and work on body and suspension, and wait for it to die. (It might live longer than me though!) I also wonder about the cost. For all the money I would spend on the rebuild and improvements, I could probably find a nice small block somewhere, that is already injected, and drop it in.

I eventually plan to have the Jeep on 35's with a SOA lift, with ox lockers or ARB's front and rear. I would have to wait on the gears until I was ready for the lockers. With 2 babies and a wife, on military pay, it could be awhile.

[CJ7Pilot]

I rebuilt my 258, added a 4.0 HO head, MOPAR MPI, and a Borla header. I get pretty good performance, but it was an expensive way to go.

A friend of mine has an '89 Wrangler, and faced with the same set of decisions, he chose to swap in a TBI 350. There was a little more fab work involved, but it only cost him half what I paid for my upgrades, and he has quite a bit more power, and oddly enough, better fuel economy.

If I were starting fresh... I'd swap in a TBI 350.

Ma'a Salaama.

[Saltydawg1]

Which engine you want really depends on how you plan to drive and use the jeep.
The 258 is a workhorse engine, not a drag racing specialist. It makes good power at low rpm ranges and the inline 6 engine design is very durable. They have tons of torque and power for low speed rock crawling and general off and on road use. They are good dependable motors but nobody is going to walk up to your Jeep and see you have a 258 and go "OMG I can't believe you have a 258 in there !!"
If you want to drag race or do a lot of high speed sand runs and such then you might consider a v-8. The shorter stroke and overall design of the v-8 engine sacrifices a little low end torque for the ability to really turn it on when the rpms climb.

They are both excellent engines, well suited to a Jeep. The 258 will be easier on the wallet and a lot fewer headaches getting to the end result.

[curbcrawler]

Thank you for your service. you could do the 4.0 head swap. You also could get some head work done to your 258 head (can be expensive) put some larger GM valves in to make it breath better get it ported and polished, maybe have the head shaved to bring up compression. Go with a weber or motor craft carb from the junk yard. Go with a after market cam and lifters to take advantage of that higher compression and improved breathing, go with a high performance intake manifold to let it breath. Get an exhaust header and cat back system. Ive done most the above and love my 258 huge difference in power. Still need to get head work done. .02

[Happy Joe]

The 258 can be as strong as you want it;
If we knew more about the jeep it would help (*hint* fill out your profile *hint*).
Personally, I would not keep a vehicle without injecting it (that goes double for an off road vehicle). I did inject a 258 and while it was not easy (around 1989) it was not particularly difficult. Depending on your mechanical abilities I would search for junk yard injection both here and on the web, for more info. The subject has been covered in depth and there are some excellent how-tos out there.

If you are a horsepower addict swapping in an injected V-8 is only a bit more complex; but be aware that you will likely have problems with the rear corporate 20 axle (a friend spun an axle flange merging onto the freeway the day after we did a 302 install) and the front D30 is known for coming apart when used hard with a healthy v-8 and large tires.

Folks seem to get good results with a 4.0 HO head swap on the 258 but be aware that you must plug water jacket passages in the bottom of the head to do this. Again not particularly difficult for the mechanically inclined.

You almost certainly have a D20 narrow track rear axle; I would replace it with a flanged axle D44 before doing much else. Gear to the tire size and 35s can be made to work well (requires a relatively substantial lift, and some driving care to make the D30 front last with a healthy 6). I always recommend a rear TJ flair retrofit for 33" tires and larger to preserve the sheet metal and tires.

If the 6 is relatively healthy and you can be satisfied with horsepower in the 150-190 range; I would inject it (multipoint), do a head swap, change out the cam, check the bearings an run it for a few years (be aware that these changes may make it fail some emissions tests in some areas principally the visual inspection). During this period I would decide on other issues like; degree of extremeness in your wheeling future, modification budget, tire size gearing and axles, transmission, etc.

Enjoy!

[78CJFIVE]

Alright, I'm sold. Going to keep the 258! I'll make her look pretty! Sorry about the missing profile, I took care of it. =)

Now, I want it rebuilt, and I want to make some upgrades. What will give me the most bang for my buck? My goals are to increase horsepower to one day turn 33's and possibly 35's, fuel inject it, and hopefully gain some MPG.

Also, does anyone know of any good machine shops or mechanics to do the work in the Ft. Hood, Austin area?

[green cj 78]

Ditch the turd, put in a. AMC 304 with the fuel injection kit. Its the cheapest way to get some power and reliability.

Low HP and problems. There are a ton more aftermarket products for the AMC 304 and cheaper too. I used to have the 258, the problems began with the carb. I replaced the carb with an MC2100. The exhaust manifold is notorious for cracking. The rear main seal always leaks, and upgrade options are starting to thin out.

[BrockGrimes]

I run 33"x14.50x15 Superswamper tsl's on a stock 258 and it'll spin the tires in the dirt.
33's aren't a problem. I'm in the process of doing the junk yard TBI swap, it's stupid easy.
You can even skip the hard part of wiring and just buy a harness for about $300, then just scrounge the
rest. Rebuild the motor swap a junk yard TBI setup and enjoy.

[wendell]

You don't need no stinken fuel injection to make a 258 run and be dependable. You add FI, then you have to worry about the computer, sensors and electric fuel pump and all that crap. I swapped a holley truck avenger 470 4 barrel, offy intake, comp cam, HEI and header, It's a little power house with gobs of lowend. This summer I'm going to install a 4.0 head and rollor rockers to finish the engine off. The holley TA series 4 barrels are made for off road and can take some extreme angles, more than I care to give it. With a carb, it's easy to tune and work on, the engine remains very simple, but with big power. You don't have to worry about a sensor going bad in the middle of know where. My repair kit consist of a roll of duct tape and some baling wire ha ha. The 258 is capable of some awesome power, but not so much that it tears up the rest of the drivetrain like a V-8 can. A well bulit 258 and the proper gears and you'll be climbing tree's if you can reach the first branch hee hee. Just another option for you to think about. Also I want to thank you for your service, you guy's and gal's have done an awesome job over there. You have the heart felt respect of a greatfull nation. Thanks again and stay safe!!!!

[curbcrawler]

Originally Posted by wendell

You don't need no stinken fuel injection to make a 258 run and be dependable. You add FI, then you have to worry about the computer, sensors and electric fuel pump and all that crap. I swapped a holley truck avenger 470 4 barrel, offy intake, comp cam, HEI and header, It's a little power house with gobs of lowend. This summer I'm going to install a 4.0 head and rollor rockers to finish the engine off. The holley TA series 4 barrels are made for off road and can take some extreme angles, more than I care to give it. With a carb, it's easy to tune and work on, the engine remains very simple, but with big power. You don't have to worry about a sensor going bad in the middle of know where. My repair kit consist of a roll of duct tape and some baling wire ha ha. The 258 is capable of some awesome power, but not so much that it tears up the rest of the drivetrain like a V-8 can.A well bulit 258 and the proper gears and you'll be climbing tree's if you can reach the first branch hee hee. Just another option for you to think about. Also I want to thank you for your service, you guy's and gal's have done an awesome job over there. You have the heart felt respect of a greatfull nation. Thanks again and stay safe!!!!

x2 think about it, if you go with a v8 you will have to change your rear end and probly the front too if you run any thing over 31". That being said, first thing I did was buy a better carb and put a header and high flow muffler on it. Instant bolt on power. Its all about letting that motor breath in and out easier. next
I rebuilt the motor and put a cam in it. this opened the intake and exhaust valves more than the stock broom stick (cam)did. more power. bigger valves, Hi performance intake will allow it to breath even better. more power. the 4.o head swap will allow the motor to breath better and it will raise the compression a bit, I think.

[Evian]

Go out and buy a Chevy 350 engine and trans. It will be a lot easier than finding a dependable 360 AMC engine. Lets not forget the parts will be a lot easier to find.

[wendell]

Also you don't want a chevy engine in your jeep, you might as well have just bought a blazer. The I-6 has a certain lure about it that makes a jeep a jeep. These weren't meant to be rail dragsters, there a go anywhere multipurpose vehicle. I'm a jeep purist, I like to keep it real, keep it all jeep. The 258 is so verstile with the things that can be done, from stroker kits to TB FI, EFI and 4 barrel carbs to 6 1 barrel carbs even. The 258 makes all of it's power and torque at a very low rpm, perfect for crawling a round in the mountains and seeing some beautifull country/ It also has it's own unique sound. Because the 258 makes it's power down low, it's not as hard on drivetrains, even built. It's when 300 hp kicks in at 4,000 rpms thats parts tend to scatter. I've had many, many jeeps over the years from 4 banger to V-8's and there's nothing better, more functional, easy to work on and more satisfing than the old 258. It takes to mods so well, that you can feel the power improve with each mod you do, it will bring a smile to your face. Nothing says performance like a holley 4 barrel, it's imppresive to open your hood and the first thing everyone notices is the holley 4 barrel. They say "WOW", you have a holley on that thing. Give it some gas and you can hear that low power rumble through the header as the engine torques side to side. No big deal on a V-8, but quite imppresive on an I-6. Even with all the mods, it still sounds like a jeep. It's really quite satisfing. Anybody can make a V-8 run, but to get power from a 6 with a carb is imppessive. It's plenty quick on the highway, but crawling a round in the hills is where it really shines, just a slow steady rumble of power at your toe. Bleep the the throttle and the frontend jumps up, thats just plain cool. There's also some really cool 258 valve covers out with air cleaners. I have the black aluminum finned valve cover that says jeep and the 13" black finned round air cleaner that says jeep on the holley, I'm going to have the valve cover tapped to fit my 4.0 head, it looks to good to give up. The engine dresses up nice, sounds good and runs aewsome, it just doesn't get any better than that. Sorry this is so long, I get carried away talking about the 258, I have such pride in mine. I've had a few 258's, but this is the first one that I have modded and I love it.