258 to 360 swap

[Kali]

I have many questions regarding the I6 to V8 swap, but the primary one is this: do any of you know of a write-up or thread that has "complete" information for the swap?

I searched ifsja through google and every thread that I have found has bits of info here and there (as well as many replies that read "search the forums there is plenty of info on this").

I can't seem to locate a write-up or near-comprehensive swap thread. Anyone have a direct link to one of these threads that so many have referenced?

OR, if anyone would like to add in their knowledge here, to the best of my ability I have found this info:

-258 motor mounts need to be cut off and replaced with V8 mounts
-V8 radiator/core support panel will need to be swapped in
-transmission crossmember will need to move, but there should be pre-drilled holes for it
-driveshafts may need to be lengthened/shortened
-wiring harness may need to be altered, or swapped

Is that really all there is to this?
For reference, I am going to be swapping OUT the 258/727/208 from my 82 J-10 and swapping IN a 360/T18/208 from an 83 J-20. Both trucks are complete in my yard right now.

Thank you!

[mwood65]

Swap?

I have a 74' Cherokee with a 258 & a 86 Wagoneer with a 360....

The Cherokee get ok gas mileage...

The Wagoneer gets.....well.....I should just buy a gas station!

Something to consider and be ready to pay for after the swap just so ya know.

[Kali]

Yeah I definitely expect it to be a gas hog, but this is also a "for fun" truck. My Ford Focus is my DD

I have a 74' Cherokee with a 258 & a 86 Wagoneer with a 360....

The Cherokee get ok gas mileage...

The Wagoneer gets.....well.....I should just buy a gas station!

Something to consider and be ready to pay for after the swap just so ya know.

[tgreese]

I would go 4.0L with the T-18 and associated bits. The 258/727 will be really slow, and I can't blame you for wanting more power. The T-18 will be more efficient, but it can be a chore to row in stop-and-go traffic. The V8 T-18 has the long input shaft, but you can switch to a short input shaft from a Ford that will be the proper length to work with an inline 6. Parts Mike has a kit. A 4.0L swap will give you a lot more highway power (near the 360 on paper) and much better economy. Plus the 4.0L HO engines come with the excellent Mopar/Bosch multiport fuel injection, which is a huge advantage over the antiquated carbureted 360 V8.

Pardon me if I offend, but I think you may be slightly naive or a bit lazy or some of both to think that there will be step-by-step instructions for this swap that are better than what you have found. Maybe your google-foo is lacking - here is a link that returns 14,700 hits https://www.bing.com/search?q=site%3...ZI&form=MOZTSB - change the key words a bit and you'll find lots more. There is a parts book online at www.oljeep.com that will show you the part numbers and configuration of each model. The pictures in the online parts manuals aren't great, but the corresponding manuals for sale in hard copy at BJs should be better. http://www.bjsoffroad.com/Parts-Books_c_149.html The parts manuals may also be available on CD-ROm from RockAuto, but I have no idea about the quality of the illustrations in that format. You also have the two vehicles sitting side by side, which is the best reference for conversion that you could possibly have. There are way more V8 FSJs out there than sixes, and someone who had to have V8 power likely would buy a different truck, or go SBC. Driver's drop T-18 equipped J20s are pretty scarce as donors go. Production volume of the Jeep trucks was something like 50-100x lower than Ford or GM, so you have to expect even less coverage online or in the popular press.

[Kali]

Naive may be correct, but I have seen some extremely thorough write-ups pass through these forums and was hoping that one existed for the 258 to 360 swap. I would prefer the term hopeful.
I have found a ton of threads that discuss the swap, but very few replies of substance (the vast majority of replies are people referencing previous threads by suggesting the use of the search function), and nothing close to a detailed list of expected changes. It seems an above average thread on this topic is one where several replies can be piecemealed into a single to-do list. That doesn't feel very comprehensive to me.
You are correct, though, having both trucks right in front of me should give me every advantage to get this swap done correctly.
You have given me something to think about with the 4.0L-HO. I have never heard this 360 run, so I don't really know what condition it is in. I was expecting to go the rebuild route anyway, but I suppose it's worth considering keeping it a six.
I could never sell this truck--I drove it home across the country with my now deceased father. It will either please me as-is (which it does), or it will get altered. After all, I am lucky enough to have the 83 J-20 donor sitting in my yard already...

[Cecil14]

Go with the 4.0L, it's definitely the best bang per buck and effort. Tons of options and aftermarket for the 4.0L, and it is literally a drop in for the 258 (plenty of threads around on that, I know I've discussed it a few times). As Tim mentioned, you can swap in the MPFI which is SO much goodererer than any carb can ever hope to be. Just grab the full system from a '91-'95 XJ or YJ and you're in.


aa

[Mikel]

Go with the 4.0L, it's definitely the best bang per buck and effort. Tons of options and aftermarket for the 4.0L, and it is literally a drop in for the 258 (plenty of threads around on that, I know I've discussed it a few times). A Tim mentioned, you can swap in the MPFI which is SO much goodererer than any carb can ever hope to be. Just grab the full system from a '91-'95 XJ or YJ and you're in.


aa

I would add whatever modern OD transmission that came with the 4.0, assuming that the truck is geared low enough to benefit from overdrive.

[tenoverthenose]

I recently replaced my 4.2 / 727 with a 4.0 / AW4 and wish I had done it sooner (I kept my 208). Theres a good amount more power and the extra gear is great on the highway. As others have noted, ditching the carb is a good move too. I'm really appreciating the FI as a travel up and down in elevation.

[joe]

For reference, I am going to be swapping OUT the 258/727/208 from my 82 J-10 and swapping IN a 360/T18/208 from an 83 J-20. Both trucks are complete in my yard right now.

Thank you!

Only thing I got is when you do the swap use the T18 from the donor 360. Otherwise you'll need to change out the different length input shaft in your 258's T-18.

[wiley-moeracing]

go ahead and swap out since you have all the parts already. the front driveshaft you may be able to use from donor but you may need to replace the rear if it is from a long bed into short bed. the wiring harness, motor mounts and core support should be swapped over also from donor otherwise you should have all you need. all these responses about installing a 4.0 is ok but they did not read or comprehend that you have the donor rig with the setup already?

[Cecil14]

go ahead and swap out since you have all the parts already. the front driveshaft you may be able to use from donor but you may need to replace the rear if it is from a long bed into short bed. the wiring harness, motor mounts and core support should be swapped over also from donor otherwise you should have all you need. all these responses about installing a 4.0 is ok but they did not read or comprehend that you have the donor rig with the setup already?

We all got it just fine, we offered up a better, less work involved, and more cost effective solution.


aa

[wiley-moeracing]

how is it less involved or more cost effective when he already has all the parts he needs right there and paid for? that's all the nuts, bolts brackets, wiring harness, motor, trans, transfer case, driveshafts, mounts, etc. and it all bolts in without modification or custom work and be done in a day or two versus finding a good motor and trans and purchasing it, making a custom wiring harness, fuel system, mounts, trans and transfer case shifter, drive shafts, nuts and bolts etc?

[fsj454]

Time

All it will cost is time. Wiley you are 100 % right

[Cecil14]

how is it less involved or more cost effective when he already has all the parts he needs right there and paid for? that's all the nuts, bolts brackets, wiring harness, motor, trans, transfer case, driveshafts, mounts, etc. and it all bolts in without modification or custom work and be done in a day or two versus finding a good motor and trans and purchasing it, making a custom wiring harness, fuel system, mounts, trans and transfer case shifter, drive shafts, nuts and bolts etc?

Assuming all those parts are good? As mentioned, Kali has never heard that engine run, and I would guess then never driven it. The condition of all parts is suspect at that point.

A running 4.0L is peanuts for cost, and a fraction of the swap that 360 will be. All the factory parts will work fine on a 4.0L. No custom anything required, short of grinding two tiny divits in a stock intake manifold. MPFI can be swapped on later, if desired. The OD trans could be swapped in now, or later, again as desired. The 4.0L gives a ton more options than the 360. Now you tell me which will be more involved? Swap the engine alone, leaving everything else the same? Or swapping the entire driveline, and all the tiny misc things that come along with it? Seems like an easy answer to me, but by all means, contradict me.

None of us are against the 360 swap, it's been done more than a few times. None of us have the answer to the original question either, including yourself, or we'd happily post it up.

Kali expressed interest in the 4.0L swap once it was mentioned, so we provided more info. Nothing more or less about it than that.


edit: my mistake, the 4.0L exhaust manifold and a new downpipe would be required for the 4.0L. Getting pretty crazy custom there, though.


aa

[tgreese]

All it will cost is time. Wiley you are 100 % right

There is an opportunity cost too ... by choosing the drive train he already has on hand, the OP is missing the opportunity to install a drive train that has significant advantage over the one he has on hand.
Some people have lots of time and little money, others not. To me, the components you use are a one-time cost that become cheaper and cheaper compared to your total expenses, the longer you own the truck - so you may as well pick the best you can afford today. Up to the OP to decide.