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New to Scramblers... need more power

4

4giglz

Basic User
City
Groveland
State
IL
Hi all,

I'm new to the Jeep thing and am having a hard time finding information about making power from an 1981 Scrambler with a 258. It has less than 70K and is in good shape.

I read the about putting the 4.0L head on the 258, and that seems interesting.

What has worked for you? Best bang for the buck? Any links to information I should read? Would a V-8 swap be better?

Just wanting to put together a fun weekend toy. Probably won't take it rock crawling or to the drag strip or anything like that, but I would like it to be more spry.

Thanks ahead of time for your input.
 
Welcome.....
While I satisfied my need/want for more power with an AMC 360, others have said the difference was amazing when they added an HEI distributor and an MC2100 carb to a 258. It will depend on what your needs/wants are in the power department. Good Luck...
 
I got fed up with the crappy plastic leaky rocker cover, so I'm swapping in a 360 instead!
 
I'm not sure what the 81's had, but if you've 2.73 gears in your axles, consider going to a better ratio. 2.73's and the 258 are not a happy combination.
 
I did both of those and it was a nice increase, but I don't know about amazing. Great upgrades with little effort and reasonable cost.

Swapping in a 4.0/AW4 got me to amazing though :)
 
4giglz said:
Hi all,

I'm new to the Jeep thing and am having a hard time finding information about making power from an 1981 Scrambler with a 258. It has less than 70K and is in good shape.

I read the about putting the 4.0L head on the 258, and that seems interesting.

What has worked for you? Best bang for the buck? Any links to information I should read? Would a V-8 swap be better?

Just wanting to put together a fun weekend toy. Probably won't take it rock crawling or to the drag strip or anything like that, but I would like it to be more spry.

Thanks ahead of time for your input.
Click to expand...

Welcome to the site Eric!

Go for the gusto and put an AMC 401 in there! :smokin:
 
I would say swapping to a HEI ignition and a TBI injection from Howell or MC2100 if you want to stay carbed.

That will give more reliability, and make sure everything that goes into the intake makes it through the engine and putting out power.

Those two additions are easy and not too expensive.

Adding a 4.0l HO head is a nice step up and then you can go to MPI injection for a little more power.

You could swap in a running 4.0l engine from a Cherokee and get MPI with some more HP. Keep the Aw4 automatic if you want an OD transmission.

Get a 4.0l from a Cherokee and build a stroker with a crank from a 258 Jeep.

Swap in a 360/401 from an old full size Jeep, probably have to rebuild it.

Swap in a Chevy 350, with whatever power adders you want.

Swap in a Chevy 4.8/5.3/6.0 from a Chevy truck in. Good mileage and nice overdrive.

That is a short list of upgrades that you can do. It is in assending order of effort required. Also keep in mind that with more power you will have to start looking at driveline upgrades to keep putting that power to the ground.

For a nice reliable daily driver, I would do line one and call it a day. You might also look into replacing engine gaskets as needed because with a 25 year old vehicle the will be drying out and leaking.

Welcome to the site, stick around, and have fun.


Carl
 
Thanks for all the input!

Many of the suggestions I either hadn't heard of or thought of. Definately food for thought. I like the idea of the HEI ignition and TBI. Where do I get the HEI from? Also If I added a header and open the exhaust a bit, I'm sure it would probably add something. Any good sources for a header?

I think if an engine swap is the way I end up going, I would probably skip the 4.0 and the fuel injection and choose one of the V-8 options. I think I would also go carbed. I'm getting a bit more "Old school" in the recent years. Another project I am trying to get going is my 1984 RX-7 with a rotary. Already have the Dellorto side draft set-up.

If I go V-8, where would be a "preferred" source for the conversion parts?

When I get the chance, I'll have to post some pics of a friend's CJ-7 with the 1998 Ford Cobra DOHC V-8 installed. Still getting it together, but it is in there!

Eric
 
So with the idea of the Carb and HEI that would be a good choice.

Both can be had from eBay. They HEI's ready to roll are about $100, figure $300 if you want a Davis name Brand unit as opposed to a Chinese copy. there is a guy selling rebuilt Motorcraft 2100 Carbs with instructions for about $300.

You can go cheeper and do the Chevy 6 cyl HEI conversion. Lots of info on the web. Then you can also get a Junkyard 2100 and rebuild and fit to the intake.

All depends on the ammount of time you want to spend on parts hunting. For me I would go with the eBay stuff and keep going. Time can be precious.

As for a 258 headder there is Clifford, and several others out there. All about the same, and will require you to mod the exhaust.

If you are going that route I woudl serriously look into the 4.0l head and then you will have to get a 4.0l exhaust which will most likely be something like a banks headder anyways.

Do the Carb and HEI and see how you feel then.

BTW, if you decide to go with a 304/360/401 AMC V-8 the belhousing will bolt straight up to the new engine. The 258/4.0l share the same pattern as the V-8's. Also early CJ-7's were offered with a 304 so you can get the same engine mounts as those to drop right in. But if it were me I would upgrade to MORE's Bomb Proof mounts for about the same cost.


Carl
 
Hey guys, im new to the site but had some questions relating to this topic. Keep in mind, im no mechanic so lets keep things fairly simple lol.
Iv recently been trying to get a hold of a scrambler, so as of right now i have 2 questions.
How does the 4.0 i6 from a cherokee compare to the 258 powerwise?
and how difficult would it be to swap in the 4.0?
 
Tomcat723 said:
Hey guys, im new to the site but had some questions relating to this topic. Keep in mind, im no mechanic so lets keep things fairly simple lol.
Iv recently been trying to get a hold of a scrambler, so as of right now i have 2 questions.
How does the 4.0 i6 from a cherokee compare to the 258 powerwise?
and how difficult would it be to swap in the 4.0?
Click to expand...
Hey, new MI guy! Welcome!

I just did a 4.0/AW4 swap this summer: https://www.cj-8.com/forum/showthread.php?t=23251

Hard to guage what "difficult" means to you. Getting the motor and/or tranny mounted in the Jeep is not hard at all, just put CJ motor mounts on the 4.0, adapt whatever you need (bolt on deal in most cases) and drill any new holes needed in the crossmember.

Getting the wiring done CAN BE difficult if you're not familiar with wiring and electrical diagrams. That's why I made the spreadsheet I did as I went along to ID the wires/connectors for swapping in a 97 OBDII setup. A pre-96 OBDI would be a bit easier to deal with (slightly simpler wiring and easier to hook up the check engine light), but with no emissions inspection in MI, the OBDII was fine for me.

If you're good with diagrams and electrical stuff in general, it's not hard to get a 4.0 running. Thinning out all the unneeded wires from the harness is where it can get more interesting, but a slow, steady effort can get it done.

There's tons of info on here and there's an entire forum dedicated to 4.0 swaps on www.cjoffroad.com. ALL KINDS of reading to do on most any topic related to the swap.

As for power, I'm thrilled with the difference. I've ridden in V8 powered Jeeps and it's not comparable to that, but it's a massive improvement and I don't have a single complaint. With 35s, 4.56 gears and the 4.0/AW4 (which addded overdrive as compared to keeping the 999 3-speed I had stock), I can do 85 on the highway at 2k RPM. That's the sweet spot for this engine :thumbsup: And once I got comfortable mashing the gas (didn't trust my work but so far ;)) I had all the power I needed to romp around Silver Lake Dunes :cool:

Welcome to the forums!
 
I also went with a 4.0 and the difference in power and reliability was fantastic. I was running D44's front & rear with 4.27 gears, 35 mtr's and the AX-15 & the 231 t-case with sye and terra-low 4 to 1. It was great on the road with plenty of acceleration and with the low gear in the t-case had plenty of power in even extreme crawling. With the miles adding up on the 4.0 and the smog laws out here in Kalifornia, I ended up putting a Hemi in it. Now THAT difference put it in a different league. We're putting out a little over 400 hp and yes, you absolutely have to build a drive train to keep power to the ground without it breaking. But gawd does it run.
 
Hi....I'm new to the forum and have read just enough to be confused on this topic. :)

I am concerned that when I get a Scrambler next year that I will be disappointed in the power output.

Looking at the options already identified above, I note that no one has mentioned swapping a Grand Cherokee V8 in (from say a '97) or is this hidden in codes above that I do not recognize because I'm a n00b?
 
Welcome to the board Irradiated Fuel! No hidden codes for noob's. Basically you can go with as much power as you want but with that there are changes that need to be made to accommodate that power.
To answer your question directly, the Grand Cherokee came with a number of engines; 6 cyl. 4.0, and 8 cyl. 5.3, 5.9, 4.7, 5.7 Hemi, and a turbo charged 5.7 Hemi in the SRT8. So depending on years there were a few options. It seems that the newer the year the more difficult the wiring and computer match ups became. I am happy with the power I have in my rig now but I did spend the money to make changes in the drive train. And remember; "With great power comes great responsibility grasshopper".
 
A wise man once said- "You can never have too much cash or horsepower."

I'm doing a 5.3 Chev swap in mine. This should give about 325HP, and decent economy. This is probably the most "bang for the buck" option, as these powertrains are fairly cheap and have enormous aftermarket support. The beauty of a Chev GenIII or IV swap is- if you want more power, the basic block architecture is the same for the 4.8, 5.3, 6.0, 6.2, and even the new LS9 Supercharged 'Vette motor. Makes upgrading a baisc bolt-in. 625 hp and 604 ft lbs of torque! Wouldn't that be a hoot!
 
Thanks Randyzzz

I've read thru your thread - just not sure that

1) I can fully appreciate all the hard work you've done (I mean that in a + way)
and
2) That I could do the swap with all the computer stuff and make it all work out right in the end.

My hats off to you.

:thumbup:
 
New to the site,but not to jeeps! As others have said, Two simple rules. ALWAYS gear the diffs correctly or all the power goodies wont work well, and big horsepower/torque increases require drive train up grades (read money HAHA!) Ive been building/playin JEEP for 30 years and JEEP really does stand for Just Empty Every Pocket!!! :D
 
Leaning towards any of these options?

giglz

Just curious if you are leaning toward any of these suggestions yet?

:D
 
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