2001 4.0 to 1991 XJ? help me!

[jbond38]

So ive been searching for quite a while now for an answer to my question. I have a 1991 XJ. I purchased a motor from a 2001 to replace it with. The 2001 has no distributor but i know i can just put one back on in place of the cam sensor. now the final question is can a 1991 XJ intake and exhaust manifold bolt up to the 2001? I know the exhaust ports are smaller on the 2001 so should it be able to bolt up?

 

[Tim_MN]

Assume the 2001 0331 cylinder head is cracked. Test it, or better yet replace it with a 1999 and older head. Google Jeep 0331 head.

Remove and re-use ( or replace with new ) as needed or required from your original engine: Intake/Exhaust manifolds, flex plate/flywheel, cylinder head, distributor-less ignition or distributor assembly, engine sensors, fan belt driven accessories, and/or mounting brackets.

 

[Goose_XJ88]

If you're the guy that bought the 01 motor from Josh on the NorCal FB page, the head should be fine. He took care of that jeep.

 

[jbond38]

Yes that is the one i bought. Sop thats a YES on putting a 91 exhaust and intake manifold on the 2001 0331 head?

 

[ehall]

Most of this stuff all bolts up although there can be some varience in things like bosses and studs that require some correction. There might be some issues with exhaust manifold that require some grinding but it should be fixable. If you got the late-model intake manifold with the engine, you would be better off moving your sensors to it, it has better flow.

I swapped a 99 engine into my 91 and had no problems but (1) there were a lot more changes in 2000 and 2001, and (2) I did not use the original headers, I used aftermarket.

You should really do some searches for previous swaps, ton of swaps here so you get first hand reports, use google with site:naxja.org for more refined results, also check the related threads at the bottom of this screen.

 

[klint96xj]

If it were me, I would swap the head out and put the 91 head on, and use your 91 exhaust manifold and use the newer intake. Everything will bolt up just fine. If you were to use the newer head, you would be better off buying a new aftermarket header for a 91 because it will then bolt to the head right and also the rest of your exhaust system. BUT, you will still have the less desirable head that is prone to cracking.


So to sum it all up,
Option A
Use 01 head and but an aftermarket header for 91 xj and whichever intake you want to use.

Option B swap the heads out, use your factory exhaust manifold and whichever intake you want to use.

For some reason the factory 91 exhaust manifold won't mate properly to the 01 head, but an aftermarket header for a 91 will bolt to the 91 or the 01 head. Headers like this can be had for around $200 on eBay.

It would be nice if the exhaust manifolds were all the same. Would save a lot of headache!

Hope this helps

 

[Jeepguy03]

If you're the guy that bought the 01 motor from Josh on the NorCal FB page, the head should be fine. He took care of that jeep.

Unless he put a beefier head on it, the 0331 can still crack. Not worth all that work to swap the motor if the head cracks. Use the 91 head since all your manifolds and accessories will bolt right up to it. The 0331 head will bolt up, but the exhaust ports are also smaller than the 91 head. The 91 head flows a bit better where the 0331 was built to meet stricter emissions standards.

 

[winterbeater]

x2. Doesn't take abuse to have a cracked 0331 head.

 

[Devilfrog]

The 91-99 exhaust manifold will not seal properly to an 01 head. You either need to make an adapter plate ... or run the 91 head on the 01 block. The port mismatch is pretty obvious. One could try using an 01 gasket headside and another 91-99 gasket manifold side (so use two gaskets), but have never heard back as to longevity like that. There used to be a guy that made an adapter plate, not sure if he still does though.

And no ... an aftermarket head for a 91-99 also will not work, I wish it was so easy. There are 00+ headers available, mainly marketed for TJ's as they used the same port configuration but ran on into 2006, whereas the XJ died in 01.

 

[Talyn]

And no ... an aftermarket head for a 91-99 also will not work, I wish it was so easy.

Why not?

 

[Devilfrog]

That was supposed to say header, damn spell check on these phones.
Can't fix it now...

 

[Talyn]

That was supposed to say header, damn spell check on these phones.
Can't fix it now...

Still, why won't an earlier header not work on the 0331 head?