4.0 to 4.2 swap: Is it possible to get the torque converter seated properly?

[tygersquirt]

Hey y’all, let me start off by saying I am new to this forum, I’ve attempted multiple times in asking my question to a few YJ Facebook groups but they all seem to just say “send it” to my questions. I’ve heard pretty good things about this forum so here goes; (and I apologize if this has been answered before, I’m still learning this site and the search features.

I have a 1994 Yj 4.0 auto. I threw a piston rod through the block and oil pan. I just recently picked up what I thought was another 4.0, but as my research shows, it is actually a 4.2. The PO I bought the motor from stated it was a 4.0, and I didn’t do my due diligence to actually check. Not a big deal. The bottom block is definitely a 4.2 as it has a pilot bearing and my old motor does not. I removed the bearing, but my torque converter does not seat properly into the engine (sorry, new to engine swaps so I’m still learning the names of parts.)

My question is it at all possible to get the torque converter seat properly? Or am I at a loss? Any help would be greatly appreciated. I double checked that the head was indeed a 4.0 as my exhaust and manifold bolt up perfectly with no need for fabrication/alterations.

Here are photos of the 4.0/4.2 and the depths that the torque converter seat into the engine.

 

[Flyer58]

I can't answer but will ask if a 4.2 torque converter that fits the crank end will work with you existing transmission?

 

[tygersquirt]

I can't answer but will ask if a 4.2 torque converter that fits the crank end will work with you existing transmission?

Thank you for the reply! I’m not entirely sure if that would work or not, but it’s a thought.

I just recently figured out what the issue was, which was a little obvious once I realized what I was working with. The PO put a 4.2 crankshaft in the 4.0 block. I took both engines apart today and getting the “new” one machined next week and will be installing my originally 4.0 crankshaft. I did a quick bolt up to ensure it spins freely and it’s a perfect fit. I’m actually happy it wasn’t a “plug and play” deal as I had hoped. The #5 piston was starting to break away and I would have had the same issue a few months down the road..