I've recently become the new owner of a '94 Dakota. 3.9 V6 M/T 4x4. For a truck that's approaching 30 years old, it's in great shape! However, it has 230k+ miles on the original 3.9 V6, and I'm seeing some leaks and hearing some noises that hint at an engine rebuild in the future.
Or... after doing a bit of research, it looks like the 5.2 V8 is a pretty easy swap! I have several other projects, so this will probably be a gradual "grab parts as they turn up" process, not a sprint to completion. However, I wanted to run through what I (think I) know now, and maybe get some feedback from folks to help plan this out.
1. 5.2 engine. We have a few decent yards nearby and I can get a running engine from a wrecked truck for pretty cheap. Ideally I'd just freshen up the top end. It looks like anything from 92-96 will work? Since the 3.9 and 5.2 are very similar blocks, can I retain all my accessories and accessory brackets from the 3.9?
2. ECM from a 5.2 M/T 4x4 truck (PN 56028263). I've seen a few of these remanufactured for about $300. I'm comfortable re-pinning my harness for the two additional injectors (I've built a few harnesses from scratch). I have a 1994 FSM on the way for wiring diagrams.
3. Exhaust. I'll probably pick up a set of factory manifolds with the engine. I can fabricate the rest of the exhaust myself. Will probably do a y-pipe, cat, muffler, and single exit - as close to factory as possible (also means I can use the same hangers).
4. Front suspension. Here's where my lack of knowledge about torsion bar setups shows. I know on a truck with front springs I'd need heavier springs for the extra weight of the V8. Do I need to swap parts with a torsion bar setup, or just adjust the bars?
5. Electric fan, radiator, and shroud modification (or removal). I think an efan is the way to go (makes for better throttle response). I believe I'll need a radiator from a V8 truck (but please correct me if I'm wrong). Also, I'm pretty sure the V6 radiator shroud won't work without modification, but I can figure that out.
I know some folks might chime in with suggestions for more power (cam, 1.7 rockers, dual exhaust with headers, etc etc) but I'm planning to retain the original transmission (which should be the AX15). I'm not trying to put down huge power numbers or hit the strip/track, so the AX15 will do fine behind the 5.2. I like wrenching, and I figured for a bit of extra time and money I could have a neat project AND a more capable truck.
Thanks in advance for any feedback or info!