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1993 Jeep Wrangler YJ V8 Engine Swap -Parking Garage Motor Swap

Posted in Project Vehicles on September 1, 2009
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Photographers: Steve Roberts

Swapping a V-8 into a Jeep just isn't that difficult anymore. Heck, you could basically do it in an office building parking garage with no more than basic hand tools. Thanks to aftermarket support for Jeep vehicles fabricating motor mounts and scrounging junkyards for the radiator with correct outlets and enough capacity to cool the new engine that still fits your Jeep is a thing of the past. Even fuel-injected swaps are easier than ever with numerous companies offering engine-specific, plug-in harnesses.

We had a '93 YJ that needed an engine. We knew we were going to bigger tires, so we went hunting for a cheap V-8 from the same year or newer vehicle. We found one in the form of a '94 Chevy Caprice that was formerly a cop car. For only $1,000 we got a car packed with a 260hp LT-1 V-8 and a 4L60E transmission that we were actually able to drive to make sure the engine was in good working order. The transmission slipped, but we were still able to peel out at will, the engine had good oil pressure, no knocking or other horrible sounds, and no smoke out of the tailpipe.

We then took the Caprice to our office building, parked it on the second floor of our subterranean parking garage and set about looking for parts that would allow us to bolt the engine into our '93 Wrangler with no fuss. The idea was that if we could do it in our office, there is no reason why you couldn't do it at home, at your apartment, or even in a Walmart parking lot.

We hit a few snags on the way, most of them related to specifics concerning bigger axles with our no lift Jeep and an engine that has less aftermarket support than the more popular LS-series that came later. We cheated here and there by using some cordless tools, but at the end of the day, we were right, and it is totally feasible to get an engine swap done with only hand tools.

This engine is going in our YJ on 40s, and this story is the first of a mutli-part series where we will take the Jeep home and be building a monster Jeep in a tiny garage. The whole point is to prove that you don't need a ton of high-dollar tools to build a really cool rig. Since this is part of a series, you'll notice that the engine isn't running, and all the "T"s aren't crossed. We don't even have a transmission bolted to it yet. But the engine is in the Jeep and the major issues with a fuel injected swap are addressed.

The bolt-in saddle mount kit from Advance Adapters (PN 713087) is designed to put a GM V-8 and auto trans in a Jeep YJ. It takes all the guessing out of locating the engine. After cutting off the existing engine mounts with our trusty cordless reciprocating saw and cordless grinder, we bolted it up. Then we noticed that the tube was a thumbs width from hitting our swapped-in high-pinion Dana 44 front axle. Once the engine's weight was on it, the tube hit the axle. The centerline of the pinion on this axle is between 2 and 3 inches too far to the passenger side, since we only cut down one tube to make it the right width. If you have an axle with the pumpkin in a more stock location or have a lift, you won't have a problem.

A little issue we ran into was the interference of the cradle's engine mounts and the A/C compressor. Our Caprice-sourced LT-1 has all the accessories on the passenger side of the block and the A/C compressor interferes with where the mount needs to bolt to the block. Working with Advance Adapters, we found out that there is an A/C compressor delete for this motor (Chevy PN 10115875), which solved the interference issue, but takes away the ability to either run A/C or use the A/C compressor as an on-board-air compressor.

With the above issues, we ended up using a more universal mount from Advance (PN 713007). Since we knew where the engine needed to be thanks to that cradle mount, we located the new mounts front-to-rear, but raised it an inch for more drivetrain clearance. Drill a couple of 3/4-inch holes through the bottom of the frame (use a Uni-bit) to get the wrench to the back side of the frame-side mounts to hold the nuts, then bolt (AA suggests welding, if possible) the mounts using two 7/16-inch bolts per side. Now, we can reinstall our A/C compressor and Trasborg can keep his dream of an air-conditioned YJ.

The engine ran great and didn't smoke, but it did have some leaks that needed to get taken care of. We knew we needed an oil pan gasket, valve cover gaskets, timing cover gasket, some gaskets in the water pump, and something having to do with the distributor. Before we even pulled the engine out of the Caprice, we ordered a head set gasket kit (HS 9966 PT-2) and a conversion set (CS 9966) from Fel-Pro. This way we had all the gaskets on hand we were likely to need, and we were able to re-seal the engine while it was hanging from the cherry picker, rather than wrestle with it once it was in the Jeep.

We tapped Advanced Adapters again to keep the new engine cool in the form of an aluminum Chevy V-8 conversion radiator (PN 716691-AA) and a 2070cfm SPAL fan with aluminum mounts, a wiring kit, and a thermostatic controller (PN 716670). We were originally looking at a mechanical fan for this setup, but there isn't a provision for a mechanical fan on the LT-1 and while there is a kit available to convert it over, by the time we'd have ordered the OE parts from GM to complete the conversion, it would be a couple hundred dollars more than this setup. The Caprice wagons had a mechanical fan setup, so you could go that route if you can find one in a junkyard.

We have used Painless Wiring kits in the past for complete Jeep re-wires, and while the kits are of high quality, we often find ourselves with more wires than we know what to do with left over. This is the first time we have used the company for a fuel-injection wiring harness, and we are very happy with this LT-1 kit (PN 60502). Basically, feed it power and ground, and then plug in all the stock GM parts- from the computer, to the sensors, all the way out to the individual injectors. All the connectors just plug in, as they should, and wire length is spot-on.

Both the four- and six-cylinder multiport-injected YJs use the same fuel pump assembly that is capable of feeding a stock fuel-injected 5.7L V-8. Our problem came in when we saw what kind of shape our YJ pump was in after all this time. We had a TJ pump hanging out, which uses the same Bosch pump as the YJ unit, but has some additional benefits. The silver section is spring-loaded, so an impact to the bottom of the tank won't crush the pump and it holds about 2-quarts of fuel so in extreme off-camber situations you don't starve the engine for fuel. We picked up a TJ fuel pump mounting ring from Gen-Right Off Road to test fit in the Gen Right fuel tank we already had in the Jeep. We discovered that the TJ pump is 1 3/4 inches taller than the YJ pump, which means we'd have to cut a hole in the floor or drop the gas tank skid down about an inch to clear it. Neither is an option, so we decided to hold off on that decision until we've got the axles under the Jeep in their final location before cutting huge holes in gas tanks.

Maybe we need to read fine print better. For whatever reason, we thought that the radiator would be a direct bolt-in for our application. Such is not the case. The mounting flange interferes with the headlight buckets and holes need to be drilled for mounting. So, out came the grinder and drill again. However, once we had the radiator in hand and were involved in the mounting it makes a lot of sense to have the end-user drill the holes themselves. With so many variables from Jeep to Jeep, there is no one mounting location that will work for everyone. We aligned the edge of the mounting flange with the top mounting tabs on the grill, and after clearancing and drilling we used some stainless steel bolts to mount it up to prevent oxidation of the aluminum.

Even though the Chevy computer is waterproof and was originally mounted in the engine compartment, the Painless kit includes a grommet to pass the wires through the firewall and the computer plugs are on the interior section of wiring harness. We wanted to take a page from the history of Jeep design anyway, and mount the computer where AMC located the computer for the computer-controlled carburetors in the CJs and early YJs. It is a tight fit, but it works great and will keep the computer in better conditions than it's ever seen before.

Due diligence is a legal term that refers to care a reasonable person would take before entering into a transaction. Yep, we didn't do it. While we actually did read the directions and discovered that we would need the Caprice brake light switch (PN SL821), we didn't want to pull half the dashboard apart to get to it. What we missed was that we would also need the fuel pump relay (PN AR272) and cooling fan relay (PN AR172). The above part numbers are the Napa part numbers we ended up buying, to the tune of about $52.


Painless Performance Products
Ft. Worth, TX 76105
Advance Adapters
Paso Robles, CA 93446
(800) 538-6272
Gen Right Off Road

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