mugwump5

This forum has been an invaluable resource for me over the last 6 months or so. So, in an effort to repay the resources of this forum, I'm going to outline my 4 cylinder to V-8 swap in my 1994 Jeep Wrangler.

Starting point: 2.5L, manual transmission, 4WD with 160,000 miles.

Donor vehicle: 1994 Trailblazer 2WD, 5.3L, 4L60E.

mugwump5

So, we stripped a perfectly good Trailblazer. We took everything with full intentions of using it all. I'm a frugal guy, and since I paid good money for a donor vehicle I planned on getting the most value for my buck. And that's my assistant.

I chose this vehicle because it's been in the family since new and I knew the service history. It's been well maintained and a solid performer. Plus, stripping a vehicle like this lets me get EVERYTHING I might need at once. Hopefully, we won't be making a series of junkyard trips to finish this off.

mugwump5

Now that the donor power plant is out, it's time for a few upgrades. After some research, I selected a Lunati 262 camshaft. Because, why not?!? And an Advance Adapters Kit to mate the 4L60E to the NP231 transfer case. You have to change both the output shaft of the transmission as well as the input shaft of the transfer case.

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Ok, time to get this mess put together. Out with the old.....

I wasn't intending to take the fenders off, but it was only a few more bolts after the grille and radiator was removed. And yes, I took the engine-transmission-transfer case out as an assembly.

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So, in with the new for a test fit. It slides in the same way it comes out. And it fits shockingly well.

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The oil pan hits the front axle. But the transfer case sits exactly where it was when I took it out. Oh, I didn't mention that I measured it all, including propshaft angles? So, I mounted the Trailblazer frame mounts to the Jeep frame. The frame was actually about 2" wider in the Jeep.

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So, back out with it. A GM 5 quart oil pan, PN 19212593 gives me lots of clearance.

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But, there is no dipstick hole in the block. Apparently, some LM4 blocks don't have a drilled hole. Most of them are supposed to have a plug you can knock out. Not this one........

You've been warned. Luckily, it is an aluminum block. Remove the manifold to give yourself room for the drill. Remove the pan you just put on and fire up a 3/8 drill bit. And, yes, I missed dead center from that casting.

And then you can tap the manifold bolts you broke.....

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Ok, the motor is out of the way. So this is a good time to clean up that engine harness. I chose to add some 8-way metri-pack connectors to interface the engine and PCM to the Jeep. I also re-purposed a now-unused relay and added additional power feeds from the Jeep underhood fuse and relay center.

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I finished welding the mounts and added additional gussets to the frame.

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And back in with the power train.

I added senders for the coolant and oil pressure guages. For the coolant, I simply added another sender to the rear of the RH head. I'll ground one side and wire the other to the gauge. The oil pressure sender is tapped into the oil cooler bypass in the pan.

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The fuel system turned into a little more than I wanted. I thought I could just splice into the existing fuel lines. But, taking it to 60 psi and finding factory hoses with worm clamps made me re-think that.

You can, carefully, splice the nylon fuel lines with quick disconnects using steady pressure and a heat gun. I used a flaring tool base to hold the nylon and a caulk gun to press the tube into the nylon.

Now I get to drop the tank and do the same to complete the plumbing.

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The Jeep didn't have power steering. Since the motor had a pump, I sea no reason not to upgrade. A stock gear and hoses work fine.

Of course, when you bump the reservoir and knock the nipple for the return hose off, you get to install a new fitting.

mugwump5

I'm not sure why the pictures fell off the last few posts. I'll add them soon. So, as of today, my Jeep hasn't run in 34 days. I have to drop the fuel tank and finish the fuel lines and then it's on to modifying the engine wiring harness to plug into the Jeep. After that, it will be shifters, exhaust, and cooling system. But, I plan on test-firing it after the engine harness is mated to the Jeep!

TJ/LS3

I will be subscribing to your build. Do you need to meet emissions?

mugwump5

No emissions in SC!

So, I've completed the wiring and the fuel system plumbing. I also modified the water pump to install a Trailblazer 6 cylinder thermostat that points almost straight out.

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I'm going to try posting less pictures per post.

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And, it fired tonight!! After I pressurized the fuel system to check for leaks, I plugged up the TAC module and hit the key.

It's setting a theft deterrent code and shutting down after 5 seconds. I guess I'll have to reflash the PCM sooner than I thought.

I still have a long punch list. But, so far all the research has paid off. I was able to use compression fittings for the lines at the fuel sending unit. A little creative bending and I re-used almost the entire Trailblazer fuel system. The stock Jeep pump is providing 56-57 psi.

mugwump5

Since it has drive by wire, I added a cruise lever from an 80s GM car and I will have cruise control. I wired it in with a Delco connector and straight wired it to the TAC module since the module will be mounted on the inside of the firewall next to the fuse block.

1964SS

iTrader: (1)

Cool build!

I think you've got a typo on your donor vehicle year.