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High Output 4.0 swap

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I snapped the cam in my renix 4.0 the other day, and shot it out of the block. Just thought I'd share that, becuase I've never heard of it!


Anyway, I got my hands on a high output 4.0 with 30,000 miles on it for $50. Its actually a '92 comanche, that had the frame and everything behind the cab chopped off. It ran fine, just slid into a tree and torqued the rear section of the box/frame, so he cut it off to tube it out but never got around to it.


My question is, how straight forward is the swap? Mounting should be the same if I am not mistaken, with the exception of moving some resevoirs, but as far as the wiring I have heard different opinions. Does the whole wiring harness need to be switched out, or is there a way to connect part of the new HO to the existing renix??


Sorry about the long post....thanks in advance for any responses.

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The block is the same, so bolting the engine into your truck is easy.


Beyond that it gets more complicated. The entire ignition and injection system is different, the manifolds are different, the CPS and flywheel (or flex plate, if it's an automatic) are different.


If I were doing it, I would put the Renix flywheel, head and manifolds on the '92 short block and keep it a Renix. Otherwise, you're looking at a whole lot of wiring and makeshift adaptation.

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well, Eagle is right.


If your'e getting the entire front half of the truck...well, you HAVE all of the wiring to do it. you will need to swap out all wiring in the cab and in the engine bay. so gutting your truck is basically a must.


It's fairly straighforward to "gut" the truck...everything comes apart easily in my experience.


so swap it all and be done with it. otherwise your'e looking at getting a motor apart...and while the motor's apart, you may as well take it all the way apart and check to be sure everything is OK and put new rings in it...then you have to do all the timing crap too and new gaskets.


I'm not a fan of that kind of work and I prefer swapping things in to tearing functional pieces of equipment apart.

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I'm not a fan of that kind of work and I prefer swapping things in to tearing functional pieces of equipment apart.

Heh, heh ...


six of one, half a dozen of the other. Either tear the engine apart or tear the vehicle apart. But you make a good point. It's a function of what you're most comfortable doing. I hate tearing apart a perfectly good interior, and with all the miles of spaghetti in a modern vehicle, to me replacing the entire wiring harness rates right up there on my scale of favorite things to do next to getting run over by a truck, or falling out of an airplane without a parachute.


On the other hand, the engine will already be out of the vehicle. If you'd drop the '92 engine in without tearing it down if you were swapping the wiring, why would you need to tear it down if you DON'T swap the wiring? Leave the short block intact, and just swap the head and manifolds. There are people who have just used the Renix manifolds on a complete HO engine, but the ports don't match and to me that's a bastardized solution. Taking off one head and putting on another seems to me a LOT less work than gutting the entire interior and replacing all the wiring.


Take your pick.

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