My 81 SX/4 Project with 4.0 Swap

[idahosx4]

HI All,

Well, after another failure to get my 1981 SX/4 Sport (with a 258) running somewhat reliably, I've decided to do a full tear down in the engine bay. I'm going to drop the engine out, clean/restore the engine bay, and put in a freshly rebuild motor.  While the motor is being rebuilt I will rebuild some other things (brakes) and fix and/or replace all the broken bits (rusted out floorboards).

After googling around a little, I've become most interested in swapping in a stroked 4.0 from a cherokee. I want fuel injection and a more modern engine with more horsepower. From my brief research, it looks like a stroked 4.0 is the most straight forward option. I read through a few build threads here on the forums from people that have swapped 4.0s into their Eagle. It doesn't look to bad. Some questions below:

I'd like to swap my transmission out as well. I can't remember my model (i found it somewhere online before) but I know it's supposed to be crappy. It's the one where you push the shifter left/down and forward to get into reverse. I do want to keep my transfer case though. Can I swap in a better transmission from a newer eagle but keep my transfer case? I have the NP 119 (full time 4x4 with viscous coupling). What is compatible? Also it looks like I can bolt the 4.0 engine straight to any of the eagle transmissions? With possibly an adapter?

What other major concerns should I be aware of for a swap like this? Besides what sounds like a custom exhaust? (mine is rusted out anyway, holes in the muffler galore).  Sounds like I can bolt the 4.0 straight to the original engine mounts, which is awesome.

If I get a late 90s 4.0 and get the ECU and wiring harness, will I be able to make use of OBDII?

Are there any detailed build threads of putting a 4.0 into the Eagle? The few I found weren't super detailed.

Anyway, thanks in advice for the help fellow eagle owners. I am very excited to fully restore this sexy vehicle.  I will post some pics of current state in a couple days.

[Prafeston]

I created this awhile ago. It's not for a stroker, but has some general hopeful information.

http://forums.amceaglesden.com/index.php?topic=43087.0

From what I understand it's a PITA to get the 96+ harness tied into the Eagle. The best range for going EFI is 91-95.

[casper]

i did 4.0 swap into my honeybadger sx4 last march. are you going to use the 4.0 serpentine belt set up or your stock vbelts? the alternator for alot of the 4.0's are computer controlled for voltage regulation. power steering pump iirc also has different fittings to fit out hoses/steering box. physically, the 4.0 is a direct bolt in. its a handfull, (maybe 2 hand fulls depending on your mechanical abilities) to do all of the accessories/exhaust. prafeston has a real good write up. that will all pertain to a stroker also. all a stroker is, is changing the stroke of a 4.0.

you have the sr4 transmission. i dont know those trans very well, but hear the shift tower is prone to problems, and they arent very strong. t4 is a better trans and a direct bolt in. im ditching my t4 for a recently scored t5. (5 speed version) also a direct bolt in. they will still use the same t-case.

i preffered to go to a 229 t-case out of a full size wagoneer. its 2wd, awd, and 4 low. direct bolt in almost. shift linkage for 4 low needs to be fabbed. people have talked about speedo cable clearance, as its clocked upward toward the floor. mine clears just fine.

where in idaho are you located? im in eastern oregon.

[idahosx4]

Prafeston, just read through your thread. Very helpful! Thanks, I completely missed it when searching last night, as my search-fu is very weak.

Which is better overall, the stock v-belts or the serpentine from the 4.0? Sounds like it's harder to use the serpentine from the 4.0, but I don't mind the extra work if it's worth it. My mechanical ability is pretty good. I've already done some work on the car and what I don't know I definitely have the ability to learn easily.

Excellent to hear that I can bolt on a T4 or T5. I will begin my search for one.

I've also read that certain ranges of the 4.0 have problems with cracked heads. Do you know which serial number ranges to avoid? Is that a problem for the 91-95 year range?

Wiring always sounds like a big pain. I don't care about OBDII that much, so I will just stick with 91-95.

Unfortunately I'm not in Idaho right now. Seattle area. But I went to school at University of Idaho and would love to find a job anywhere in the state. It's my true home. 

[Draekon]

Keep in mind that if you use a T4 or T5, then you will have to cut a hole in the bellhousing for the crank position sensor.  Alternatively, you could get an AX-15, but I don't know if that will work with your current t-case.

[Prafeston]

Or you can purchase a hesco cps sensor that relocates it. Also the bell housing for the t4 or t5 fits the 4.0, but you will have to purchase an adapter so the crank fits the 4.0.

[idahosx4]

I did some minor tear down tonight to prep for pulling the engine. Hood is off, radiator and fan removed. Oil drained. I haven't pulled the AC lines yet though. Has anyone had experiencing discharging AC lines? I would be very surprised if this thing still had a charge, but I don't have pressure gauges for them and neither did O'Reilleys. If it is charged, do I have to worry about just opening the valve and letting into the atmosphere? Just make sure nothing is in front of it or it will freeze right? Obviously I'll probably destroy 1/3 of the earth's ozone in the process, but no one will mind I'm sure.    

Also, I assume you just remove the bolts from the motor mount brackets that go straight into the block, so that the axle/front diff is still bolted to the brackets? Then just forward off the transmission and up?

Here's an album with some pictures. Includes the pics of my rusted out floor boards and the rusted out section in the engine bay where the battery used to be. And the swapped out passenger door. Otherwise interior is mostly pristine and the rest of the body is great! I

Pictures: http://imgur.com/a/7gfJv

[Brentmo]

I'm putting a stroked 4.0 into my SX4 as well.  I'm too busy pushing a pencil to have the knowledge and time to complete the swap myself.  I bought a remanufactured motor with warranty from S&J Engines in Spokane.  We're using the OBD1 system too, but understand it will likely require bigger injectors.  My car already has the T5 in it.  and we're also relocating the crank position sensor to the harmonic balancer instead of drilling.  Don't know what I can add, but I'll post my progress and enjoy watching your build, too.  That interior looks great.  Best of luck!

[Prafeston]

Hey, that's JSK's old SX/4. It used to reside in St. Louis, MO. Someone shipped it out your way and then sold it. I was looking into purchasing it, but the rust issues and the damage to the rain gutter on the passenger side scared me away. The seats sure do look nice!

[Baskinator]

'91-'95 is fine for a swap. The post 2000 engine is what you want to avoid for the cracked head issue. '96 up relocates the temp sensor from the head to the thermostat housing, so it's slightly different. The 4.0 will need some ribbing shaved down on the side to clear the differential bracket, and the bracket and/or exhaust will need to be modified. The 4.0 manifold needs to be modified to use a 4.2 intake, but you could go with Mopar fuel injection to solve that. It's pretty expensive if you buy the kit. GM TBI is a good, cheaper option also. For manual transmission I'd go with a Jeep NSG370 6 speed, or Auto I'd probably just stick with a TF727.

[idahosx4]

It is in fact JSK's SX/4. I've emailed with him a few times with questions. Very nice guy. A guy in oregon bought it from him, but then some bad circumstances forced him to sell. The rust issues do suck, I admit I got a bit starry eyed when I saw the posting on craigslist. The SX/4 had been a sort of dream car for me for a long time, lol. I'd seen lots of wagons on craigslist but never an SX/4 until I saw this one. I hope to cut out replacement floorboards and the piece underneath the battery from a salvage SX/4 or spirit. Not sure what I'm going to do about the rain drip rail yet.  I also need to find bumper end caps. Currently I have 1/4.  I'm conflicted about the seats. They are near mint condition, and I love them, but their are horribly uncomfortable and the foam has gone very soft. I'd love to have some real expensive bucket seats.

Prafeston/Brentmo, I've read through both of your build threads a couple times, very nice! Definitely some good info for my journey.

Baskinator: Is there a reason you can't use the intake from the 4.0? I've seen many threads where people swap a 4.0 in but keep the carburetor and 4.2 intake? Seems strange to me especially considering the crappy Carter system. I was planning on just using the stock fuel injection from the 4.0 for my stroker, along with obviously bigger injectors. It seems many Jeep owners have done this with great success for the same swap.

[Baskinator]

I just meant if you keep the carb, you must use the 4.2 intake and modify it slightly to fit on the 4.0 head. That's what I did when I recently installed a 4.0 in my Eagle. I've never seen anyone carb a 4.0 intake, and you would have to use fuel injection if you do in fact use one.

People keep the carb because it's very expensive to go fuel injection, takes a lot of extra work, and sometimes requires further modification and tweaking to use. The 4.0 offers a more highway driveable rpm range than the 4.2 and somewhat better hp, even if it is still using a carburetor. I didn't have the option on my budget, so I went with carb for the time being. Even when I do go fuel injection, I'm going to install a GM TBI which is much cheaper, easier to install, easier to tune, and has good parts availability. Nobody makes GM throttle body adapters for the 4.0 intake, so I would need to use the 4.2 intake anyway.

[idahosx4]

Ah ok, that makes sense.

In my case, there will be many $$ flowing out of my wallet for this beautiful machine.

[Brentmo]

My understanding is the 4.0 head flows much, much better than the 4.2.  A lot of people put the 4.0 head on their 4.2 and I'm told the combination makes a better motor than either.  Clifford makes an intake for using a carb (or dual carbs) on the 4.0.  It's not inexpensive, but a lot less than a fuel injection conversion.  I can see the attraction of losing all the electronics.   

[vangremlin]

I've never seen anyone carb a 4.0 intake, and you would have to use fuel injection if you do in fact use one.

Apparently a lot of Jeepers do put a carb on the 4.0 intake, and there is a supplier here in Colorado who will soon be offering the 4.0 intake for use with carbs.  He'll plug the injector holes, and have an adaptor plate to put a carb on the 4.0 intake. 

The 4.0 head, along with an upgraded cam, makes a world of difference for the 4.2, even if you stick with a carb.