Engine swap?

[Cecil14]

Crap, you're right Tim. Thanks for catching that. The Jeep NP231, at least, is left drop, while the old D20 is right. Not sure what the easiest right drop NP pattern t-case would be, but there are certainly some options there. You could swap the front axle (not terrible, if you can find a cheap donor), use an adapter to keep the D20 (expensive?), or pick through the various GM NP pattern t-cases to find something you like. I know the GM NP208 of the 80s was right drop, but I believe it had a slip-yoke, so you'd have to deal with that. You would likely have to swap the input gear for a 23 spline one, as well.


aa

[FSJunkie]

360s are cheaper to build, can be rebuild (meaning bored) more times, and run cooler than a 401.

Meaning they are a better engine than a 401 in every way except for having 20-30 less horsepower given the same configuration otherwise.

But good engines don't impress people and make you look cool. Engines with a big displacement number and lots of chrome aftermarket junk bolted to them impresses people.

[rang-a-stang]

...
But good engines don't impress people and make you look cool. Engines with a big displacement number and lots of chrome aftermarket junk bolted to them impresses people.

HAHAHAHAHAHA!!!! SSSSOoooooooo true!!! LOL!!!!

I am not a fan of shiney fandanglement, either. In fact, I have a set of polished cast Aluminium Edelbrock AMC V8 valve covers for sale if anyone is looking!

I would buy something like these (somewhat in your area)

https://prescott.craigslist.org/pts/d/jeep-cherokee-fuel-injection/6442678643.html

https://phoenix.craigslist.org/evl/cto/d/87-jeep-cherokee-xj/6445790192.html

https://phoenix.craigslist.org/wvl/cto/d/1987-jeep-cherokee-xj/6441119148.html

https://phoenix.craigslist.org/evl/cto/d/jeep-grand-cherokee/6442396858.html

Park it next to your truck, swap parts, then when your Cherokee is up and running on EFI, you part this one out (get a couple hundred $$ back) and junk the hulk. Saves you trip after trip to the wrecking yard searching for parts that "probably" work and ends up being a little cheaper...

[80Limited]

I paid $300 or $350, I can?t remember, for the XJ I took the trans and t-case out of. Then parted it out and made my money back and then some.

[mwood65]

Wow

You guys sure cleared up all my confusion.....not..

J/K... just alot to think about.

I have huge wants, little means & little ambition.

Since I am disabled I am limited on how much work I can actually do so the easiest route would be better (and cheaper)

[rang-a-stang]

I define easy as: Least parts to buy/change, least steps to complete, least cutting/welding, and least research to do. You also defined the original post as
"I want to put in a 401 but keep the T18 & Dana 20"
or
"I would really like to swap to an automatic"
I would summarize that as "I want a V8 and an automatic". A big step in keeping it "easy" is to either buy a parts rig that has a complete drivetrain or get the whole drivetrain together.

Summary:
1) easiest=stay with what you got and fix it but you don't get either a V8 or Auto
2) next easiest=360 or 401/TH400/QT because you can bolt it in, no adapters, no axle/gear changes, no re-wiring, no cutting/welding, no cross member fabrication, etc. If you get a parts rig, you have everything to bolt it into yours without any drilling or cutting.
3) After that it starts opening up. You could do 360/TH400/Dana 20 but more work is involved. You could do like you said and just upgrade your engine for more power. Me personally, if I were in your shoes, I would watch for a parts rig on Craigslist or on the classifieds here. That way you get the drivetrain (auto/V8) and the other things that add up on a swap cost (exhaust, shifter, radiator, etc). Plus if you do a 360 or 401/TH400/QT you have the advantage of all the experience of folks on here and the service manual which tells you how it should work and how to fix it and the other parts on the rig (maybe it has other parts you need or other parts you can sell to help offset to the cost).
I know Wiley-Moe is selling a TH400/QT that he used to race, on this forum for cheap. He also has (or at least HAD) a 401 for sale, too so check the classifieds. So many options!!!

[rang-a-stang]

Here's everything but the trans for $300:

https://phoenix.craigslist.org/wvl/cto/d/jeep/6442562904.html

[mwood65]

The more I thought about it and read your peoples replies the more I realized I don't know what the hell I want.....

I like the 258 but just need a little more grunt....not a lot, just a little.

I want to keep it old school with no computers or electronics so that rules out a 4.0 swap.

What about just swapping gears to something like a 4.10 or so?

Just keep the 4.2 and go with lower gearing?

That seems like a deal maybe for $300 but I would have trouble getting it up the hill to Payson. I would have to rent a U-haul and car hauler...

[ZackN920]

Ok, if your not too interested in swapping that much, but want a little more power... How about a 4.0HO head swap?

They seem to be popular among the Eagle and Wrangler crowd that have the 258 and want some extra grunt. From the research I had done (when I was considering buying an Eagle about a month ago) a 1992-1997(?) head is what is most sought after.

Supposedly, just swapping the head is worth about 40HP over the stock 258 output. Add the 4.0 cam (or a custom grind) and you can bump that up even more!

You'd have to do more research though, for what intake and exhaust to use. I can't remember those details...

[Cecil14]

There are quite a few pretty easy things you can do to the 258 to beef it up. First thing you need to know, though, is what shape the bottom end is in. You do not want to drop a nice fresh head on a worn out bottom end. The increased seal up top will cause a lot of blow by the worn rings.

You want a '91-95 7120 casting head. Have a machine shop give it a once over, do a decent valve job and drop it on. There are a ton of write ups about the swap. Most people claim you have to seal off some of the water jacket ports in the 4.0L, but I'm not so sure. I have never compared the 258 and 4.0L heads side by side, but it seems like the head gaskets were nearly identical last I looked. Your mileage may vary.

Next up is cam. My personal preference is the Comp Cams #68-231-4 for a carbed motor. I would degree it, mine have always been a few degrees off when installed "straight up".

You'll have to run the 4.0L exhaust manifold if you switch to that head, which will require some reworking of the down pipe as well. I got a really nice tubular style manifold off ebay quite a few years ago for pretty cheap that has served me well.

You've got several options for intakes; you can stick with the stock intake (details), Offenhauser makes a really nice 4 barrel intake (same details as the stock above), or I've even seen some people put a carb on the stock 4.0L manifold. I've never tried that, so I can't comment as to the success.

After that, it's just a matter of picking your favorite carb. I've run an MC2100/2150 before with great success. The 258, regardless of what you do to it, will not require much more than that. I've seen a couple people around recommend this seller on eBay, saying he will build a carb to your specs even: eBay carbs. The 1.08 venturi carb is more than enough for a 258.

Lots of other things you *could* step into (pistons, compression, stroke, etc.), but those all start to get pretty involved. A stroker would probably be the next step I would recommend, you can keep it carbed, but again that is a lot of work.

[wiley-moeracing]

You said you may want an auto due to disability? if you put and auto behind that 6cyl you will zap a lot of horsepower to run it. if you do need an auto the cheapest best alternative is to put the 360 v8 in it with the turbo 400. you can keep the dana 20 if you want by changing the output shaft ( which a overhaul is a good idea) and a new adapter or change transfer case to a quadratrac. you will need driveshaft modifications either way, a different radiator and v-8 motor mounts, all of which you can find used here in phoenix area. you can call me if you have more questions and need parts, thanks Tim

[mwood65]

Made a decision..

I am going to keep the 4.2 and just pull it and go through it.

Freshen up the one I have with some machine work and
New bearings & rings,
Replace the cam with a better one,
New oil pump, water pump, timing set
Do the 4.0 head swap
and of course some pretty AMC blue engine paint!


Now........I don't suppose there is anyone in the central Arizona area that would love to help me rebuild the T-18??/

Dana 20 is fine just needs a gasket set.....

[Cecil14]

You said you may want an auto due to disability? if you put and auto behind that 6cyl you will zap a lot of horsepower to run it. if you do need an auto the cheapest best alternative is to put the 360 v8 in it with the turbo 400. you can keep the dana 20 if you want by changing the output shaft ( which a overhaul is a good idea) and a new adapter or change transfer case to a quadratrac. you will need driveshaft modifications either way, a different radiator and v-8 motor mounts, all of which you can find used here in phoenix area. you can call me if you have more questions and need parts, thanks Tim

Honestly, you're way further ahead running an AW4 if you have to swap anything in. It's plenty strong enough for anything a stock I6 or even V8 will put out, infinitely more efficient than the TH400/TF727 offered originally, has OD, and I believe uses a lockup converter (don't quote me on that, but pretty sure). Realistically, you have to run an adapter for a t-case anyway unless you want to run a QT, which is getting REALLY expensive anymore. Plenty of right hand drop NP style cases around to choose from with no adapter on the AW4, or even just a flipped D300.


aa

[Mikel]

I am going to keep the 4.2 and just pull it and go through it.

Freshen up the one I have with some machine work and
New bearings & rings,
Replace the cam with a better one,
New oil pump, water pump, timing set
Do the 4.0 head swap
and of course some pretty AMC blue engine paint!


Now........I don't suppose there is anyone in the central Arizona area that would love to help me rebuild the T-18??/

Dana 20 is fine just needs a gasket set.....

Not my business, but you are going to spend a significant amount of money rebuilding a drivetrain you really don't want?

[yossarian19]

If you are going to do rings & bearings, and you want an auto etc,
get a 4.0 + AW4, do rings & bearings on a stroker, and run an AW4. My $0.02. V8 torque and a 4 speed auto with lockup.