My XJ is an '88--came with a 4.0L that had been beat by the previous owner, so gave up the ghost at 160,000 miles.
I've always been a hot rodder with the belief that cubic inches were everything. So, putting those two "needs" together with the requirement that the 4L needed massive help to be reliable (another need) again, I chose the Chevy 350 as a replacement. Why the Chevy 350? Massive after- market support, both within the "go fast" community as well as the off-road fraternity, AND, it's a reasonable fit into the relatively small XJ engine compartment. Choosing the 350 immediately puts you down a path of significant upgrades if over-all reliability is also a "need"; and it was/is with me. Cooling a V8, axle strength, what trans? With regard to what trans, the easiest install is to use the auto that generally comes with a donor--I searched high and low for an '88 or newer (Calif smog laws require donor engine to be same year or newer than the engine being replaced) for a 350/manual trans donor. Nada. My '95 came from a 4l60e equipped Blazer. This meant that I had to also swap the PCM that came with the engine with an ECM that was originally used by GM in a manual trans application, AND certified to be used with my selected trans--an NV4500. I "had" to have the NV4500 because of the low first gear--around 5.6:1--and the high overdrive.
I stated earlier one must be tuned to the smog requirements of their specific locality. I new about the "same or newer" rule, but didn't find out about "package certification"--GM had to have put the combination of engine, including intake and exhaust manifolds, and transmission into a vehicle CERTIFIED to operate in Calif. Well, GM never put an NV4500 in any car. This was interpreted by the local smog "cop"(the official, by the way, that you MUST have inspect and test your completed project if you need to get it registered) to mean I must use the 1/2ton truck engine, complete with TBI and the stock truck exhaust manifolds. Since I had already purchased a new NV4500 and Advanced Adapters' bell housing, etc to match it to my yet to be purchased TPI engine, I continued down the path allowing me to keep the NV4500. First, I had to obtain documentary proof that GM did in fact install an NV4500 behind a 5.7L in a 1/2 ton pickup, for use in Calif. No easy task. Now, when it comes to putting the 350 into an XJ, every one tells you, you must use early car exhaust manifolds to deal with frame clearance (or headers, which are not smog legal). This is because the engine needs to set low between the frame rails so that the hood will close. I suppose you could set the engine above the frame rails and modify your hood to clear, but raising the engine above where the Advanced Adapters' motor mounts places the engine causes all kinds of other fitment/alignment issues. Well I'm here to tell you installing truck manifolds are doable but not for the faint of heart. I had to cutout large sections of frame rail on both sides to get adequate clearance. Reconstruction of the "butchered" frame was tedious and extremely time consuming--I used a TIG welder for this whole process because I could control the heat and weld more precisely than with MIG; Tigging metal that has been plated for rust prevention adds a whole new meaning to "patience". I also had to cut out the upper control arm mounting brackets to clear the manifolds, and construct custom drop brackets for both upper am lower control arms. Using a radius arm set up would solve the need to construct drop brackets, but I had already fabbed drop brackets some time ago, so I only needed to change how I attached the dropped UCA bracket to the now massively chopped UCA mounts. I'm a little goosy about the strength of my new UCA mounts, but will address this issue when I install my "new" reverse-cut (high pinion) D44 I'm currently building to replace the D30. Additionally, the O2 sensor on the manual trans applications mount on the driver's side exhaust manifold--right up against the frame. This required cutting a hole in the frame and building a tunnel to clear the sensor--the smog guy was impressed, but would not have passed on the installation if the O2 sensor was elsewhere, such as on the cross over pipe, where it was on the auto trans application.
I could go on for pages about each and every
"new" challenge addressed as I wove through this conversion. As an example, finding an ECM and the correct EPROM that was certified for operation in Calif was next to impossible; however, after TONs of research I found a way that satisfied the smog guy, but that's another story.
So can you install a 350 into an XJ? Yes. Is it a drop-in? No! Would I do it again? Differently!! The majority of my problems were do to SMOG laws in Calif--other states??--given this is were I live, I would probably use the the "world class" version of the Borg-Warner T5 trans instead of the NV4500. Since I believe (I didn't spend too much time researching) the T5 was available behind a 350 in a Camaro, meaning you could legally use Camaro exhaust manifolds, which would solve 90% of the fitment problems I encountered. But I have to tell you, I love the crawl ration the NV4500 gives me, and the overdrive is better than the AX15 or the World-class T5--best of both worlds. The 3550 is a choice if your local smog guy will pass on it. GM never used it. Ratios are similar to the AX15.
I hope this long-winded follow-up response gives you a little insight into the complexity of installing a 350 into an XJ. It's by no means complete, but should give you a better idea of the ease of installation other than a simple "yes" you can.
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