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Old 12-08-2018, 04:21 PM
mwood65's Avatar
mwood65 mwood65 is offline
258 I6
Join Date: Jul 17, 2017
Location: Arizona
Posts: 336
Crazy thoughts?

If you guys go back and read all my posts from day one you will be hard pressed to know if I am getting senile or am just confused most the time.

The truth is I don't know what I want most the time and it changes daily.

Here's the deal basically, I have a 1986 Grand Wagoneer with a 360, 727 and whatever TC comes in them. It's nice to drive, quite nice interior and body is not bad. I am having nothing but problems with the 360, one little problem after another. I would say it's only 40% reliable.

I have a 1974 Cherokee with a 258, T-18 & Dana 20
The Cherokee drives and rides like....well, A 1974 truck would.
It's crude, basic and although 110% reliable it isn't what I would call fun to drive for any length of time.

What I would like to do (I think) is put the 258 in the Wagoneer and have a nice vehicle that's nice to drive, it would get better mileage and be reliable.

As far as I think I know, The 258 will bolt right up without any issues except maybe a different torque converter due to balancing differences. Is that correct?

Putting the 360 in the Cherokee is a different story because it won't bolt right up to the T-18 correct? It would need a different input shaft maybe or pilot bearing?

Or should I sell them both and just look for a 258 Wagoneer???

Any opinions would be appreciated. I don't have much more auto work in my tired old body and need to just do something so I have a super reliable vehicle that I don't have to work on all the time just to try and keep it going.
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Old 12-08-2018, 04:54 PM
bufurd's Avatar
bufurd bufurd is offline
327 Rambler
Join Date: Apr 13, 2008
Location: ashland wi.
Posts: 548
We are all a little different than most... I wouldn't mess with both of em, if ya want a 258 in the wag put one in it. Then you'll have 2 reliable Jeeps, according to some that's remarkable.
Current fleet
Abner-73 He started it all in 1979 (plow truck now)
Bufurd-69 Fixed up to take Abners place as DD
Delta-70 Built for fun, 455 Olds, T-18, D-20, 4:10 gears
Humpty-74 J-20 4BT, NV4500, 30+MPG
07 JK Wife bought new...
13 Grand Cherokee Trail Hawk, wifes new ride
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Old 12-08-2018, 05:13 PM
Ristow Ristow is offline
Join Date: Jan 20, 2006
Location: The Great Googley Moogley Midwest.
Posts: 17,071
the 258 uses different frame horns that the motor mounts bolt too. they can be swapped over.

i'd keep the V8 in the GW however.
Originally Posted by Hankrod
Ristows right.................again,

Originally Posted by Fasts79Chief
... like the little 'you know what's' that you are.

Originally Posted by Fasts79Chief
I LOVE how Ristow has stolen my comment about him ... "Quoted" it ... and made himself famous for being an ***hole to people. Hahahahahahahahahha!

→ Where the kids hang out... come for the mindless chat,stay for the hand drawn emoticons.

It's like you're unraveling a big cable-knit sweater that someone keeps knitting...and knitting...and knitting...and knitting...
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Old 12-08-2018, 05:58 PM
gpcl16 gpcl16 is offline
232 I6
Join Date: Apr 02, 2016
Location: California
Posts: 121
Originally Posted by mwood65
Any opinions would be appreciated. I don't have much more auto work in my tired old body and need to just do something so I have a super reliable vehicle that I don't have to work on all the time just to try and keep it going.

If that's your end goal I think your best option would be to sell both jeeps and buy a Honda or Toyota. "Super reliable" and "30+ year old jeep" are two terms rarely used in the same sentence.

In all seriousness though, there shouldn't be much difference in reliability and maintenance between a 360 and a 258. And swapping in the 258 would likely be a marginal fuel savings. The bigger fuel savings would be swapping in a manual trans over the slushbox 727.
1988 Jeep Grand Wagoneer
4" BDS Suspension Lift
Tru-Trac Rear
Howell GM TBI with Custom Tune
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Old 12-10-2018, 11:46 AM
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rang-a-stang rang-a-stang is offline
Join Date: Oct 31, 2016
Location: Camarillo, CA
Posts: 3,130
I think my opinion is similar to others. I would focus on one for now and park/sell the other. If you like driving the G-Wag, just focus on getting it reliable. I think it would be easier to make the G-Wag reliable than it would be to make the Cherokee Comfy.
79 Cherokee Chief, barely runs
(Cherokee Build Thread)
11 Nissan Pathfinder Silver Edition 4x4
09 Mazdaspeed3 Grand Touring
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Old 12-10-2018, 12:57 PM
joe joe is offline
Join Date: Apr 28, 2000
Location: PNWet, USA
Posts: 22,376
If'n were me I'd put the 258 in the wag. I like the 258 six. Not a lot less power but if maintained ultra reliable and IMHO plenty adequate for a DD wag. It'll never be a zoom zoom high reving rocket motor but you can spruce them up a bit with carb/ign mods.
"Don't mind me. I'm just here for the alibi"
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Old 12-10-2018, 01:20 PM
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Cecil14 Cecil14 is offline
Join Date: Jan 22, 2001
Location: Carson City, NV
Posts: 5,094
If you're going to the trouble of swapping in a 258, then swap in a 4.0L/AW4/whatever you want (NP231s work just fine for part time 4wd). 258s are starting to get harder to find, while 4.0Ls are still everywhere. 4.0Ls have a ton more power than 258s, and even carbed should get better mileage (though that should honestly be the last consideration here). You can drop in the MPFI very easily, if you're so inclined.

The swap is not going to be free, even if you already have the motor. The trans sits in a different spot in the 258 and 360 equipped rigs, so you'll have to move that, meaning different driveshafts as well. Exhaust will have the change, radiator, I believe the fuel lines come up on opposite frame rails between the two?

If you have your heart set on swapping motors, there are way better options than the 258. LS swaps come to mind, if you're really looking for reliability.

If cost and reliability are your biggest concerns, you really are better off selling the jeeps and getting something more modern. Second best would be simply addressing the issues with the 360. Swaps are quite a ways down the feasibility list for this one.

1983 J-10 - 4.6L(MPFI)/CS130D/Hydroboost/NV3550/D300/44/44/3.54/Disc-Disc/32s/42 gallon 'burb tank
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Old 12-10-2018, 03:43 PM
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tgreese tgreese is offline
Join Date: May 29, 2003
Location: Medford MA USA
Posts: 11,133
A 258 with an automatic and GW gears is going to be very underpowered. The six is longer and moves the transmission and transfer case further back, so the crossmember location and driveshaft lengths change. There is more to it than just bolting it in.

I expect you won't see a major increase in gas mileage, partly because the aerodynamics won't change, and partly because you will be driving the 258 at full throttle all the time.

I kinda doubt there is any path forward for a GW that gets better mileage and is cost effective, unless you plan to drive it another 300K miles in the next few years. You could go diesel, or multiport small block Chevy (the LS?). With the Chevy, you'll get better mileage but not as good as the original Chevy truck, due to the higher drag of the GW platform. The 4.0L is a great swap for a 258-equipped Jeep IMO, but it's still an old design pushrod six though the Mopar/Bosch factory multiport fuel injection is excellent.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination ATs, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
ECO Green: '15 FCA Jeep Cherokee KL Trailhawk
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