Powertrain Swappin'

After nine months of prep work, I was finally ready to tear into the Jeep and get the swap done! The old 258 wasn't getting any more fun to drive, and I was getting sick of staring at that nicely dolled-up 5.0L just waiting to go in.

And so it began... The setting is the driveway in front of my parent's house, right in front of the garage where all the parts have been stored. Those of you who have visited me before may recognize it as the same place I did my axle swap last year. My folks had left the day before for three weeks of vacation, so I had room to breathe if the single week I took off work wasn't quite enough time to get everything done. Little did I suspect...

Oh, did I mention that my Jeep is my daily driver? If this didn't get done before my folks came home and my dad needed his car back, I'd be in some serious trouble with my boss at work!

Here's the last known "before" picture, just before I started:

Step 1: Disassembly

Ripping everything apart went pretty quickly, and was intensely gratifying. Off came the fenders and front clip, to get all the access I could. Then the tranny and transfer case came out, using Larry Soo's floor jack and Gord Pritchard's transmission jack adapter - both invaluable tools for this kind of work. Then I disconnected the exhaust and all the wires and hoses from the engine, removed the motor mount bolts, and hauled that old 258 right out of there!

Yes, I've already sold the York compressor setup that you can see on the old engine. Can I interest you in my old clutch?

Step 2: Cleanup and Jeep Prep

Since everything was so nice and accessible, with the front of the Jeep basically stripped to the frame rails, I took the opportunity to wire-wheel off all the rust and gunk I could see on the frame, and gave it a coat of Hammerite. The firewall and fenders got the first good washing they'd had in years, too.

At this point, my good friend Thomas came by and lent me a hand for several afternoons and pretty much whenever else he could stop by to spend a few hours getting greasy. This was payback for a favour I did for him during the summer. Thanks again, Thomas!

"While I was in there", and the access was so good, I took the opportunity to do a few upgrades. In went a '73 Blazer heater motor to upgrade the mediocre YJ one. In went a rebuilt '78 Ford Continental 4-wheel-disc-brake master cylinder, to improve the fluid flow to my rear brakes, which had been lacking. That M/C bolts right up to the YJ booster, by the way - a good upgrade. And on went a pair of F-450 front shock towers, replacing the lousy welded-on YJ towers and giving me a good 3-4" of extra front shock travel. The old towers came off without too much hassle, using an electric die grinder.

Step 3: In Goes the 5.0L

Ah, the moment of truth. Finally, the new engine hung in place, more or less in position in its new home:

The first picture is yours truly, removing the shock tower he cleverly installed before getting the engine moved into place. The photo in the middle is my friend Darryn illustrating an important lesson: be very careful when moving an engine on a hoist around, especially on a gently sloped driveway. We almost tipped the whole works over once, moving it into place. That would've been really depressing!

The last picture is the two of us rejoicing that it's finally in place. Really.

When it came to choosing exactly where to locate the 302, I basically just centered it between the frame rails, and then placed the fan in the YJ's fan shroud, leaving about half an inch between the fan and rad. I wanted to get it as far forward as possible, to maximize my rear driveshaft length. After that, it was just a matter of drilling the final holes in the motor mounts to lock everything in place, and then installing the mounts.

Step 4: In Go the Gearboxes

At this point, Larry stopped by to lend a hand, so I quickly put us to work getting the tranny installed. Before it went in, I bolted the first adapter (with its gasket) onto the tranny, and then bolted the NP203 reduction box to the other side. The bolts for the NP203 had to be put into their holes in the adapter before it was bolted to the tranny, since there isn't enough room there to install them afterwards. Took a couple of tries before I got this sorted out, naturally.

Oh, and the bellhousing and clutch were bolted to the tranny before installation as well, along with the clutch fork and throwout bearing. After much pushing and shoving (and cutting of my YJ's floor pan), in it all went. Voila:

Next in were the second adapter and the D20 transfer case. Some very careful assembly was required. It has to be done like this:

Bolt the adapter to the D20, after installing the D20 input bearing and snap ring into it, and after placing the D20 input gear (loosely) into the case.
Remove the D20's rear output assembly (tailhousing), yoke and all.
Drive the NP203 output shaft (with the output gear, bearing retainer plate, bearing, and snap ring in place) into the adapter, picking up the bearing and input gear as it goes.
Install the snap ring onto the end of the shaft through the hole in the back of the D20 (this is why you remove the rear output assembly).
Re-install the rear output assembly back onto the D20, being careful not to displace any of the roller bearings.

For all the care we took making this adapter, for the life of me I couldn't remember how I'd intended for all this to go together! There was much swearing and outright horror going on before I finally figured these steps out.

Anyway, with this last chunk together, in it went, and the adapter was bolted to the NP203. This whole setup only really works because the 203's output shaft (and gear, and bearing retainer) can be slid as one piece into the rear of the reduction box. Otherwise, I can't imagine how it could possibly be assembled (using plate-type adapters like mine, anyway).

After all the gearboxes were in place, I designed and installed the skidplate mount, and then bolted on the skidplate itself. Even with my 1" skidplate drop in place, there's about 1" of clearance between the second adapter and the center rib in the skidplate, and maybe 1/2" between the top of the D20 and the underside of the body tub. Pretty close...

Step 5: Some Other Miscellaneous Stuff

With all the heavy lifting done, it was time to do some lighter work. Now I could finally measure the lengths for my new driveshafts, so I did. I had my front CV shaft (originally from a '98 TJ) shortened about 4", and had an '85 Bronco front CV shaft shortened to fit in the rear. I found this shaft at a local wrecking yard. It had a new slip yoke installed in it, with almost 5" of travel! I had this work done at a local driveline shop while I waited, then took 'em back to the Jeep and in they went.

Around this time, Thomas and I installed the fuel pump in my gas tank, and I hooked up the rest of the fuel hoses and vent lines, and tested the system. I also installed and bled the Ford clutch master cylinder and hose, and threw on the rad hoses, the power steering hoses, the newly re-bent tranny shifter, the gearbox vent lines, and the Jeep's front clip and support struts.
The all-Ford clutch setup worked fine, as you'd expect with all-factory components.

The accelerator cable was the right length to reach its hole in the firewall, but in order to get the pedal travel right, I had to space the cable's firewall mounting plate out from the Jeep's firewall by about an inch. The Mustang cable uses a small metal plate instead of the YJ's plastic snap-in clip, so the cable won't bolt right up anyway. I solved both problems by making a mounting bracket out of some angle iron. The cable's plate bolts to one face of my bracket, and the other face bolts to the firewall near the hole for the cable. A little tweaking was required to get this just right.

We also took the opportunity to put gear oil into all three gearboxes, make sure the engine had plenty of oil, and refill the rad with new antifreeze and water, 50/50 mix.

Here's the Jeep, with its new powertrain finally installed:

Step 6: Wiring It Up

Now that the engine was secure in its new home, I could drape the Jeep and Mustang engine harnesses in place, and make the measurements I needed for wire lengths, etc. With that known, I merged them together into one new harness, and installed it on the engine. Several of the Jeep's old harness clips helped hold the new harness in place on the firewall.

Once the harness was installed, Thomas and I marked and drilled at least a dozen holes in the firewall and fenders for mounting all the stuff that attaches to the harness, like the ignition coil, vacuum solenoids, BAP sensor, and WOT relay. We also cut the hole in the firewall for the computer "leg" of the harness to pass through, and installed the computer behind the glovebox, in the same location that the YJ's old computer had occupied. The YJ's old computer used exactly the same style of enclosure as the Mustang's, so it was a simple matter of moving the YJ's computer mounting bracket onto the Mustang computer, and bolting it in!

We also chose a mounting place for the charcoal canister on the passenger-side fender (basically the same place the washer and overflow bottles are mounted, over on the other fender), and for the oil filter.

This was also a good time to install the vacuum distribution manifold on the firewall, and plumb all the vacuum lines and hoses.

Step 7: The Moment of Truth

It's worth noting that almost three whole weeks had gone by since I parked the Jeep in the driveway and picked up the first wrench. After the first week, I was back at work during the days, and only working on the Jeep after hours and on the weekends, except for three more days of vacation time I took during the third week. It was a good thing, too, since by now it was the beginning of the third weekend! If anything went wrong now, I was in for some major trouble!

Now was the moment of truth. Would the engine start? What if I had misaligned the timing chain or something, and was about to find out the hard way, by damaging my new toy before I got a chance to enjoy it? The worry sounds silly in retrospect, but it was a stressful time... After all, there was a lot of untested work that was about to get proven (one way or another) when I turned that key!

Without further ado, I hooked up the battery and turned it over. It cranked, and cranked, and cranked, and... the battery died! Cursing, I pulled it out and hooked it up to the charger, then grabbed the battery from my sister's car and threw it in. A this point, I was a bit less than rational - I needed to hear that thing start, dammit! More cranking, this time very lively with the fresh battery. But the engine just didn't want to start. Thinking that the timing might have been out by enough to prevent it from starting, I loosened and turned the distributor a bit, sort of a shot in the dark at improving the timing.

Back to the driver's seat, turn the key, some more cranking, and with a mighty roar, it came to life!!! Woohoo! There was much rejoicing, let me tell you.

The nest morning, I started it up again and set the timing to 10 degrees, like the Haynes manual says. Then I let it warm up, and gave myself a shock as I watched the temperature needle move past 100 degrees C (210F)! Then I remembered that the cooling system was full of air, and would need some time to burp itself. After a couple of warming cycles, the temperature settled down to a reasonable level.

Step 8: Test Drive!

Before I could take the Jeep out for a spin, I had to put the rest of it back together! So on went the fenders and all the bits and pieces that mounted to them, as well as the battery tray. Then I put the carpet and center console back in, after cutting some of the carpet out around the part of the tranny top cover that pokes up through the floor. I threw in a piece of sheet metal over the rest of the opening in the floor, to keep the wind and water out until I make a proper tunnel cover with holes for the new shifters and everything.

The maiden voyage went pretty well, all things considered. I coasted down the driveway, and slowly proceeded around the block, all senses alert as I scanned the gauges, listened to the engine, and felt for every last vibration. Oh, by the way, the Jeep still didn't have the exhaust installed, so it was a loud trip through the neighbourhood. No cops in sight, fortunately!

The Jeep behaved really well, aside from being obnoxiously loud. The coolant temperature stayed rock steady, everything stayed nicely in place, and I breathed another enormous sigh of relief!

The next business day, very early in the morning, I drove the Jeep 30 kms or so to a good local exhaust shop (Muffler Man), and had them install the custom exhaust for me. Again, I was lucky not to run into any officers of the peace along the way - it was a long, loud drive, especially with the motor revving at highway speeds!

Compared to that, the drive from the exhaust shop to work was bliss! For the first time, I was able to experience the power and strength of the new engine without the distraction of the exhaust noise. It was really, really nice, and I've been happy with it ever since!

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