HotBox

I've look at a bunch of different posts and haven't seen this definitive answer

So my 01 has the 0331 head, not currently cracked doesn't leak or burn oil. It's just a very loud running engine from the bottom end. I'm looking to keep an engine in the garage on a stand to swap in case of emergencies

I have the ability to buy a low milage 4.0 from a 98 or 99 XJ. My main concern... and really only concern is how will I be able to bolt down the coil rail without the threaded holes in the block?

Ralph77

So you plan on using the head on the '98/'99 which is not a 0331 head?
You do realize there are many more things going on that need to be addressed besides how to bolt down the coil rail?
Anyway guys just fab up brackets. Here is an example.

Some guys do the Viper Coil Mod. Quick Google search will tell you everything you need to know about that.

HotBox

I guess in this case the most simple answer is to just make your own brackets, never really thought about that

Besides the could rail the only other issue I've heard about is mating the exhaust manifold, being that that earlier heads have larger exhaust ports. With the best solution being to use an aftermarket header

Other than that what are the other many issues?

HotBox

sorry if I was vague, I didn't plan to just use the head from the 98 4.0 I plan to keep for a rainy day. If something were to happen, or my lower end noise gets louder I would preemptively swap in the entire engine

I planned to get after market headers which I used in my Wrangler and had good results. And the coil rail was the other issue I didn't know how to remedy

Ralph77

Well I am still a little unclear on what you are doing.
You are putting a '98 or '99 motor in an '01?
Which head are you using on the '98 or '99 motor?

bluejeep2001

If you use the 98 or 99 motor without swapping in the 0331 head......your manifolds will not bolt up correctly.....no place to bolt coil rail as you know...you will have to remove the distributor from the new motor and install the newer cam sensor or whatever they call it on the 01's. If you just use the block from the 98/99 and install a 0331 head then no issues at all. The coil rail eliminator mod is easily done if you have only minor ability to splice in some wires

HotBox

Honestly I've heard to avoid the stock 0331 head like the plague since they are prone to cracks. I fully planned to use use entire 1998 motor and all accessories and buy an aftermarket exhaust header to match the larger ports.. this was something I read in other posts, is that not an option?

HotBox

Yes I'll be using using entire 1998 motor. Full engine swap including accessories ( when the time comes if my engine goes out)

ive read that the older head have larger exhaust ports so an aftermarket header is needed which is why I didn't think to bring it up because I thought that was the only solution to the problem

Ralph77

What are you doing with the Jeep?
DD, trail rig, etc?
For starters what are you going to do about the 4 O2 sensors?
You do know that if you keep the computer that you have to take out the distributor and put in the gear drive from the '01 right?
I get the feeling that you have not researched this anywhere near as much as you should.

HotBox

This is a completely stock daily driver

I'm confused as to why you say that. The various different threads I've read say you pull the distributor out out the 2000-2001 cam sensor will directly install in its place no issues at all


And as for my 02 sensors. again I planned to use an aftermarket header to fit the large port head, and still run the factory 2001 mini cats and all 4 sensors will be installed

This information comes from this forum on different posts. Is none of this true?

Ralph77

So better info yields better answers.
And yes you are right about the cam sensor.
Exactly what aftermarket header do you plan on running?
Not aware of any aftermarket header that will solve that problem and still let you run the dual front cats.
And if you do know of one I would really like to know myself. LOL.

HotBox

Yeah I actually just did manifold work to my Jeep a few weeks ago. I have spare parts all over the place and painted some new intake and exhaust with new 4 hole injectors.








I might be off base and I didn't confirm this with anyone but I used pacesetter headers for my 06 LJ and loved them. From outward appearance they have larger exhaust ports than the stock cast iron one so I planned to used them over again since they're for 2000-2006 4.0s

https://www.ebay.com/itm/164616014164

Ralph77

So again more info. Good.
Now I know that you have a place for the 2 upstream O2 sensors and that the dual cat will bolt to that.
I am going to assume that those headers are made for a 0331 head and in the case of later TJ's the TUPY 0331 head.
Thinking it still won't solve the bigger exhaust port problem on the 0630, just guessing here, head you will be using.
But I could wrong about this.
IMO you need this:

https://jeepexhaustadapter.com/

Also here is one thing I could never figure out. Look at the applications listed at the Ebay link.
Not an XJ in the list. And I always wondered why.
Cause best I can tell is when it comes to '00 and '01 XJ's with the factory 2 piece exhaust manifold the part number for them is the same part number for the TJ's.
So why won't it work and why is it not listed in the application?
I just assume it will despite that.

HotBox

damn that's really awesome. Thank you for the link. I didn't even know an adapter was being made

I have the original exhaust manifolds from my 06 LJ and 01 XJ side by side and they are the same part number. I can't see why they wouldn't fit, so maybe that's just me being an optimistic

the adapter is a cheaper and probably a more effective method to mate the old manifolds to the earlier heads. As you can see the ones I installed are in good shape and freshly painted so I don't NEED to replace them and the adapter will alleviate that.

this all steamed from having low oil pressure for a long time (not a huge concern) but now the lower end has started to get louder which worries me a bit.. Good compression across the pistons tho. Just getting ready for anything and since I have the space to keep a spare

Ralph77

This subject has come up more then once.
And me owning a '00 with CA Emissions and having a 0331 head as made me poke around about this over the years.
So please realize that I have no first hand experience here.
This is just stuff that I think I know. LOL.
So please keep us updated with your progress in whatever direction you do go with this.
Oh and thank you for being able to confirm another thing that I thought I knew.
That the exhaust manifolds are the same part number for a TJ and XJ. LOL.