(as published in the Flatlander's Jeep Club Newsletter)
Phase 1 - Planning your project
Spending more time here saves more time and money later. Decide: 1) what do you want your Jeep to be capable of when you're done; 2) whether used parts are as good as new; 3) what you're going to do if you get in over your head.
For me, I wanted my Scrambler to be able to run well on the road, and have enough torque to idle through most of the easy trail at our local ORV park. Any modifications had to be functional and over-engineered. I was willing to spend a little more for a new or better part so that when I got done, it looked good enough for a magazine.
2 - Engine prep
Engines come down to "pay me now" or "pay me later". If you're going to put an engine in, might as well do it right and get it rebuilt before you install it. The more work you can do yourself the more labor costs you save. There are many books and experts out there, seek them out and learn all you can before starting. Changing a cam or rear main seal now won't be nearly as painful as doing it six months from now!
I used the 360 from my wagoneer shown here. (As you can see, I chose to do the upgrade while still in the Jeep. Not the preferred method, but I was short of space in the garage). The 304, 360, 390 and 401s are all the same externally. 304's are found in old CJ-7's, 360's in a good percentage of Full Size Jeeps (Wagoneers, Cherokees, J-10, J-20, Gladiator). Not sure where the 390 came into play, and the 401 was in some mid-70's FSJs and those performance AMC cars. Some of the 401's came with a factory 4 barrel carb setup.
The decision to use the 360 came from may things: 1) I need to "keep it Jeep". Chevy 350's bore me. 2) since the CJ-7s and CJ-8s are the same up front, it will bolt right up using 304 mounts. 3) I already had the engine. "See, I'm saving money already!"
Phase 3 - Tranny prep
Unless you know a bit about transmissions, find one in good shape to start with. Keep in mind a few things: not all trannies are the same length (a change here could mean up to $400 in new driveshafts); not all trannies are the same strength - T-5s aren't a good match for a blown/injected 454. Research here will pay off as well.
If manual, get the flywheel resurfaced, a new pressure plate/disk/throwout, any seals you can get to, and change the fluid. If automatic, get an external cooler (the one in the radiator doesn't count) and a shifter you can trust. Cables are better than linkages if you're going to flex your Jeep (who wouldn't?) 'cuz they won't bind up.
I used the wag's Torqueflite 727 and a B&M Megashifter. I got a low-stall torque converter to keep temps down and keep the V-8 from blowing the driveline apart when I gun it. I installed a TCI Streetfighter racing rebuild kit. It didn't come with instructions. Don't try this at home, I am a professional. Faint of heart beware.
Phase 4 - CJ prep
Spend some time marking important things on the frame like: front of bellhousing, front of transfer case, rear of radiator, front of engine pulley. These will help you avoid surprises later. Be sure to mark every wire. Even if "well, it's the only orange one with a clip on the end" - you'll be sorry :) Remove both fenders, all the grille stuff, etc. It'll just get in the way or get damaged.
Phase 5 - Driveline swap
Take extra time to drain all the fluids. Double and triple check all wires and linkages before pulling the old driveline. Don't forget the ground strap under the engine mount. If possible, remove the transfer first to even out the weight on the lift. I rented my engine hoist to do the swap. With the number of times I rented, I could've bought one for the same price, but I'd decided that $60 four times is easier on the pocket than $200 once. Don't forget the engine leveler. Use bigger chain than you need.
Once the engine is out, you can swap out the engine mounts. If you stick with the AMC V-8, you only need to change the right side frame-side mount. Truth be known, you don't even need to change it. Welding the holes shut and redrilling for the V-8 resilient pad will save you $80. Use new resilient pads/sandwich pads/rubber mounts/whateveryacall'em. They're about $10 each from O'Rielley's Auto Parts. Change them now, it will be much harder later. You must also change the engine-side mounts as well, available from Briggs. If you go this route, the V-8 will drop into the correct location. If you're using anything besides an AMC, there will be much measuring, welding and fabrication here. Advanced Adapters are very helpful with both parts and advice.
Depending on the transmission selected, your skid plate may or may not bolt up. The transmission tailshaft has the rear support attached, so if you get a different transmission, ensure you get the support off the donor too.
Here's where you get to hope for driveshafts that fit. With the 727, the driveshafts from the T-5 equipped Scrambler worked fine. This is where I discovered that the 727's pan is shaped for a left-side driveshaft. A right-side shaft hits the pan. After several emails to folks listed on my Scrambler Registry, I found that a 4" suspension lift will fix it. So far, it has. (Gee, twist my arm. "I gotta put on the lift kit, it won't work without it!")
The ignition "brains" are different, but the plugs are the same. Don't try to run the '8 with a '6 computer (bad things happen).
Phase 6 - Loose ends, shoulda coulda
I was looking for low-end torque instead of high-revs, so I put replaced the 600 CFM with a 500 CFM. I had read that a smaller carb will help low end response. It may be my imagination, but I'd swear it's true!
Don't get in a rush at the end. Before you fire the '8, triple check every hose and fluid level. I disconnected the "brain", cranked the engine for 3 seconds. I did this a few times to get the oil flowing. Another way to do it is to remove the distributor and spin the oil pump, but I didn't want to mess up the timing setting. I hooked up the brain, dumped a cap full of gas in the carb (put the air cleaner on - a backfire can be an engine fire without it). Ensure whatever you've rigged up for an exhaust directs the heat away from your wires and fuel line (stock runs up the inside of the right side frame rail).
Rose Muffler did the custom dual exhaust for $140. I used header wrap from the manifold back to the transfer. I encourage an "H-pipe" as close to the engine as possible- an H pipe connects the left and right side exhausts. The theory is that it equalizes the pressures behind the exhaust valves, helping the intake side flow better. 4Wheel&OffRoad did an article just recently on exhaust mods and one of their findings was that the crossover made more off-idle torque improvements than all the other stuff (high-flow cat, headers, turbo mufflers, larger exhaust pipes, etc.) put together.
Take the time to dress up the engine compartment, tie up wires, paint if needed.
As mentioned, I used a Megashifter from B&M. I went through a few cables before I got the right length (4') and the right size - I needed the SuperTough size, it's about twice as thick as the one that came with the shifter.
The work continues. See updates on my webpage at http://www.jeephead.com/scram1.html
Thanks for reading along, good luck with your project!
Not affiliated with American Motors Corporation, Jeep® or Daimler-Chrysler. ©1999 OffRoad Vehicle Outfitters