92 YJ Motor in 06 TJ/LJ

[Trouble]

So, as my luck would have it, the 4.0 in my 06 LJ is getting horrendously noisy at only 86k. I always take great care of my vehicles, change the oil often, but I’ve never had a vehicle that didn’t end up having engine problems. Even my old truck with a 5.3L Chevy in it needed new lifters before 75k. I think I just have terrible luck buying vehicles that people don’t change the oil on enough, I dunno….

Based on research I’ve done I think it may be a broken piston skirt. The tick takes about 15-20 seconds to start on a cold start, and then goes away at idle once it warms up. I haven't spent the time to pull the pan or further diagnose it due to just thinking about and looking into engine swaps.

Anyways, my friend has a freshly built 4.3L stroker for a price too good to pass up. The stroker would cost me significantly less than a used 03-06 4.0L from various sources. Yes, I understand 4.3 is an uncommon stroker size, and I'm not sure why he chose 4.3 instead of 4.6 but for $750 I am seriously considering it.

He had it in his 92 YJ and it was the original motor. After pulling it out for a rebuild he decided to mildly stroke it. The work was done by a friend of his with a speed shop. He then ran the motor for about half of a wheeling season until he started having problems with it again. Come to find out the Ford injectors he was using were leaking after he shut the motor off which caused bearing failure from filling the oil up with fuel. It then went back again for a rebuild, new pistons, bearings, etc and before he could get the motor back in he scrapped his project due to frame rot. It also has new rocker arms and lifters with probably less than a thousand miles on them. I watched him replace them myself trying to chase down the bearing noise from the fuel contamination.

So, like I said, with the price he wants for it I’d have just about as much money in the machine work and parts to drop a new set of pistons in my current motor. The owner is a good friend of mine and I trust him and the builder of the engine.

My question, is does anyone know what kind of trouble or differences I’ll run into trying to drop a 92 block into my 06? I'm figuring if I swap everything from my block over to his the computer shouldn't even known anything has changed.

I know the main differences I'll need to tackle are:

1. Coil on plug ignition, I doubt his head has the provisions for mounting the rail.

2. Exhaust Manifold, he says I can use the manifold he's going to give me with the engine and change the head pipe for cheap. I'm not sure if his manifold is 6 into 1, but mine is 6 into 2 for the mini cats.

3. OPDA/Camshaft Synchronizer, I have the infamous 05-06 style with the known issues. Can I slap mine on his and run it?

4. Intake Manifold, will mine bolt up?

If anyone can shed any light I would appreciate it, I'd like to know just what I've getting into if I decide to do this...thanks guys.

[cruiser54]

XJ Cherokee and ZJ Grand Cherokee 4.0L engine blocks interchange.

2000+ TJ Wrangler and WJ Grand Cherokee 4.0L engine blocks interchange.

XJ/ZJ blocks and 2000+ TJ/WJ blocks do not interchange without significant modifications. (1997-1999 4.0L TJ Wrangler blocks will interchange in XJ/ZJ and visa-versa).

TJ/WJ 4.0L Engine blocks underwent clean sheet design changes effective in the 1999 WJ Grand and 2000 TJ Wrangler. These blocks are not interchangeable with XJ/ZJ engine blocks. The reason is motor mount bolt holes and belt driven accessory mounting bolt holes are in different locations, or not present at all, TJ/WJ vs. XJ/ZJ.

[JeepFamily]

Cruiser54 is exactly right with missing motor boss's. You will also have trouble with exhaust and intake port matching as well as water pump issues. I suspect you will easily spend the difference in headache and mods to make it work. Aside from a huge reduction in vehicle value by putting a Renix based engine in your 06.

[Cheromaniac]

Yes, I understand 4.3 is an uncommon stroker size

That's an understatement! I don't think there's a 4.3L Jeep I6 stroker anywhere on Planet Earth so your friend's friend must have an amazing level of creative genius to build one.

[Muad'Dib]

Did that year of YJ come with a 4.2L? I know that the YJ stepped over 1990 with the 4.2 just dont know the exact cutoff. Could that be what your friend has vs an impossible 4.3L?

[Cheromaniac]

The YJ had the 4.2L motor up to 1990 and adopted the 4.0L HO motor from 1991. The XJ had the Renix 4.0L from 1987-90 and the HO motor from 1991.
A 4.3L displacement is only possible if you start out with a 4.2L engine and do a +0.030" overbore (4298cc) in which case, it wouldn't be a stroker. You could theoretically build a 4.3L mini-stroker (4324cc) using the 232 crank and a +0.125" overbore on a 4.0L block but that would be a very rare specimen indeed.

[Muad'Dib]

The YJ had the 4.2L motor up to 1990 and adopted the 4.0L HO motor from 1991. The XJ had the Renix 4.0L from 1987-90 and the HO motor from 1991.
A 4.3L displacement is only possible if you start out with a 4.2L engine and do a +0.030" overbore (4298cc) in which case, it wouldn't be a stroker. You could theoretically build a 4.3L mini-stroker (4324cc) using the 232 crank and a +0.125" overbore on a 4.0L block but that would be a very rare specimen indeed.

I knew about the cutoff for the XJ, but i dont think your quite right about the YJ... i want to say they had a 4.2L up until 91 or 92.. then they went to a 4.0.

[Cheromaniac]

1990 was the last year for the 4.2L motor so it could have appeared in some YJ models that were registered in early '91 but definitely not beyond that.