xjproject:
Nope, the 4.3 isn't a "bolt in" swap - only the 3.4 comes close to being bolt in and the 3.1 motor won't work at all (usually a front drive engine with a wierd bolt pattern) as far as I know. Please understand that when you go with the 4.3 NONE of your existing drivetrain is compatible.
In a nutshell, to install the 4.3 you need the engine, trans and t-case from the donor vehicle and either the factory elect. harness with computer or just the computer and then get a new harness from Painless Wiring. Next, you'll have to get the XJ V6/V8 motor mounts from Advance Adapters. These motor mount brackets do bolt in, but require drilling. Welding is also an option. The 4.3 with the 700r4 or 5sp is a few inches longer than what you're taking out, so the trans crossmember needs to be moved back. This requires drilling or again, or making new brackets/crossmember. That'll get the new power plant mounted in place. Now you need to also get an XJ gas tank from a 90's XJ with the internal pump or buy an aftermarket electric pump. I prefer the tank with the internal - more reliable.
Cooling system is gonna need to be upgraded to a larger radiator and the 4.3 requires a return hose from the engine to the top of the radiator that you'll need to have a radiator shop add to the top tank. Also, the factory clutch fan won't clear. You'll have to get an electric fan wired to a temp sensor switch - don't go cheap on the fan - I learned that the hard way..... There are some factory fans in the salvage yards that you might be able to adapt as well, but don't use one from a 4cyl car - take one from a car that has a larger engine - it moves more air.
Another thing - the S-10 5 speed tranny's t-case lever and stick shift are a bit farther forward than the XJ's original so you'll have to cut the floorboard in two places and either modify the center console or ditch it altogether. The stick shift ends up being in a much more comfortable place with this mod, but the t-case shifter ends up tucked right under the dash pretty tight. Something else - depending upon how much lift you have, your driveshafts are gonna need attention. If you have probably 5" of lift or more, your front driveshaft will likely need to be replaced with a longer one since the t-case is a few inches farther back than the original. This then means that your rear driveshaft will then need to be a bit shorter so be sure to check the travel of the slip yoke - you don't want it to bottom out and trash your new t-case. This is a good time to install a Slip Yoke Eliminator and a new rear driveshaft.
After all that, you'll need to replace your exhaust system. The 2.8's catalytic converter isn't gonna cut it for the increased flow and heat and the exhaust bends aren't even close to try to use it until after the cat. You'll also need to have a bung welded in for the O2 sensor just after the exhaust manifold.
Once you've done those things and wired up the electrical, about the only other snag will be compatibility of the gauges or idiot lights. I tossed the factory setup and put in AutoMeter gauges and speedo - worked great.
As far as clearance issues go, all I had to do was hammer a dimple into the pass. side of the unibody behind the new motormount to clear the 4.3's exhaust manifold flange, and dimple up the floorboard above the t-case a bit because it's a tight fit. A t-case drop kit is an option, but you lose that much ground clearance.
My first XJ was an '84 with the 2.8. If I had to do it all over again, I would in a heartbeat! I like the fact that the S-10 4.3/5sp has a much heavier flywheel which makes crawling so much smoother than with the XJ 4.0. If my current rig ('93) didn't already have a decent engine, I'd do this swap again.
Hope this helps!
