86 XJ Mopar 318 Engine Swap

Hi,

new to forum, so this looks like the right place to post this question, so here goes..

I have a 1986 Jeep Cherokee, AMC 150 CID, 2WD, Aisin AX-4 transmission, 2 door. The old 150 is very tired at 251K miles. I want to put a Mopar 318 motor in it. Has any one done this? what is involved? do i need a different transmission? do i have to modify the driveshaft? is there an off the shelf conversion kit that anyone is aware of?

any help would be welcomed.

jespo

ok.....

jespo86XJ said:

Hi,

new to forum, so this looks like the right place to post this question, so here goes..

I have a 1986 Jeep Cherokee, AMC 150 CID, 2WD, Aisin AX-4 transmission, 2 door. The old 150 is very tired at 251K miles. I want to put a Mopar 318 motor in it. Has any one done this? what is involved? do i need a different transmission? do i have to modify the driveshaft? is there an off the shelf conversion kit that anyone is aware of?

any help would be welcomed.

jespo

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What year 318? Old or new? Why? YOu will need and entire driveline. Engine, tranny, and tcase! I believe. New shafts or modify yours. The only "conversion kit" that I know of for the XJ is an AA kit for a SBC 350 or 4.3! HTH!

Jespo, Probably a silly question, but why a 318 instead of a 360? It would be the same amount of work for both, may as well go for more hp and torque. Unless of course you just happen to have a 318 lying around :roll:

Jespo,

I'm sure Wiley Coyote had no ill intent by suggesting putting in a bigger engine since he believes it'd be the same amount of work - more horsepower and torque aren't very kind to our beloved XJ's without MAJOR modifications to the axles and unibody. So, I'd stay with your idea about the 318 if you're set on swapping in a V8 since it will have plenty of power.

Another thing to consider - if you haven't already - is what the emissions laws in your State allow for doing engine swaps. Be sure you've researched that entirely before you start modifying.

However, the 318 swap isn't easy at all. Ghost is correct - you'll need an entire matching driveline - engine, tranny and t-case since none of the stock XJ driveline is compatible. (Actually, I just noticed your's is a 2wd, so unless you're looking to make it 4wd - skip the t-case part).

If you want some really good 318 swap info, one of our members - Ray Pili - installed one in his early model 2 dr. But, once you see some pics of his rig, you'll understand the significant effort that went into making it work. Unless you've got alot of fabrication skills, can weld, and are willing to do some cutting, I'd stay away from a V8 conversion all together.

Now, what I would suggest is that you consider swapping in either a 3.4 chevy Camaro V6 (bolts right in) or better yet, snag a 4.3 Chevy V6, tranny and t-case from a 90's S-10 truck/blazer/astro van. I did the 4.3 swap in my first XJ, an '84 4 dr.

I loved that setup - I had a 5 speed and loved the torque of the 4.3. If you're a member, I did an installation write up that's in the Member's Tech archives. Or, I could e-mail it to ya. Lemme know.

the chrysler small block (318 360) has the same bolt pattern as the 60 degree GM v6's and the 2.5's found in cherokees. so techincally a 318 should bolt right up to the ax-4. but i personally dont think the ax-4 would hold up to the 318. im not exactly sure the output spline count between the ax-4 and the tf304 (Torque Flight, CHRYSLER) but i would think if you got a tf727 from an older dodge truck it should be the same as the tf304. so the transfer case might work. i have thought about this swap if i ever find a cheap xj/mj HTH

Arakele said:

the chrysler small block (318 360) has the same bolt pattern as the 60 degree GM v6's and the 2.5's found in cherokees. so techincally a 318 should bolt right up to the ax-4. but i personally dont think the ax-4 would hold up to the 318. im not exactly sure the output spline count between the ax-4 and the tf304 (Torque Flight, CHRYSLER) but i would think if you got a tf727 from an older dodge truck it should be the same as the tf304. so the transfer case might work. i have thought about this swap if i ever find a cheap xj/mj HTH

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The SB chrysler and the 60* gm/2.5's are not the same bellhousing.Your thinking of the 3.9L cryco V6.The Trans your speaking of is the TF904 not the TF304.
OlyWa

my 85 xj had the TF904 trans in it. My plan was to get a housing from a Chrysler bell housing trans and swap my guts into it.

Could keep all the same drivetrain that way. I never did the swap since I found a cheap 4.0L rig instead. But is should all work. The main concerns is the drivers side starter on the 318 engine will interfere with the front driveshaft. Jeep addressed this in the ZJ by making a special bellhousing that the starter bolted to on the passenger side instead of to the engine.

Chrysler ran TF904 behind a 318 all the time from the factory so it should take it fine. The 229 tcase that my rig had was also in FSJ waggys with 360cid engines so it should have also held up ok.

the 3.9 v6 is a 318 with 2 cyl's cut off. they are the same pattern. the 2.5 and the 2.8 have the same bolt pattern. the 2.5(150) offered in cherokees was the exact same 2.5 put in the dodge dakota pickup trucks. and with my expereince people have swapped the 2.5 with the 3.9,318 and even the 360 (although not with a manual the 360 is externally balanced) the manual tranny will physically bolt up but i wouldnt trust it to handle what the 318 could give it. the stock TF automatic would hold up better but i would still swap it for a better TF unit.

Arakele said:

the 3.9 v6 is a 318 with 2 cyl's cut off. they are the same pattern. the 2.5 and the 2.8 have the same bolt pattern. the 2.5(150) offered in cherokees was the exact same 2.5 put in the dodge dakota pickup trucks. and with my expereince people have swapped the 2.5 with the 3.9,318 and even the 360 (although not with a manual the 360 is externally balanced) the manual tranny will physically bolt up but i wouldnt trust it to handle what the 318 could give it. the stock TF automatic would hold up better but i would still swap it for a better TF unit.

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I stand corrected on the 3.9L,you are rite it is the 318 -2 holes.As far as going from a 2.5/2.8 to a 3.9/318/360,I'm not going to argue the point with you but next time you get a chance take a look at at them both and you'll see.
OlyWa

As far as putting a AMC V8 in a XJ the problem is the exaust.I currently have a dummy 401 sitting in the engine bay of one.It's just real tight on the passenger side.The TF727 and 208 fit nicely though.
OlyWa

OlyWaXJ said:

As far as putting a AMC V8 in a XJ the problem is the exaust.I currently have a dummy 401 sitting in the engine bay of one.It's just real tight on the passenger side.The TF727 and 208 fit nicely though.
OlyWa

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OlywaXJ, would shorty headers work for your exhaust?

The AMC 2.5 used in the XJ has a GM V6 bolt pattern. It is not the same as a Chrysler small block. It was made this way to simplify production while they were using the GM POS 2.8L V6. Chrysler never got around to changing the bolt pattern on the engine and just left it that way.

The dakota guys with the V6 are more lucky, they have the same pattern as a 318/360.

Stick said:

OlywaXJ, would shorty headers work for your exhaust?

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No they would'nt fit at all.
OlyWa