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Ignition Upgrade For 1988 Jeep Grand Wagoneer SJ 360 CID V-8 AMC Engine

Upgrading the DuraSpark ignition on a 1988 Jeep Grand Wagoneer SJ 360 CID V-8 AMC Engine to Ford TFI ignition system, including distributor cap, rotor, plug wires, and ignition coil.

Here are some images of the original ignition and early test-fit images of the new cap and rotor.

Original distributor cap and wires. Original oil-filled 'can' ignition coil. Original Duraspark ignition module. TBR by an MSD 6A? Compare the original rotor to the taller,wider TFI rotor (right). Test fitting the TFI distributor cap base adapter. Test fitting the TFI distributor base and cap. It fits!

Here's some documentation of the previously damaged air pump system. You can see where the passenger side fitting was broken off, then the hole welded shut. The broken fitting let hot exhaust gas out, which melted the main wiring harness. Some wires were replaced, but some are still fused together, bare, or covered with hunks of melted plastic loom.

Notice the plastic fan on the air pump which sits behind the pulley. During the dreaded Power Valve Incident, the catalytic converter melted and plugged, forcing exhaust gas out every available orifice, including back-feeding through the air pump. You can see the melted plastic blades. At the time, the pump was non-operational (not spinning... no v-drive belt).

I wanted to unravel the mysteries of the main wiring harness, so I removed the split loom and started tracing wires. My objective was twofold: to try to trace all the ignition-related wires in preparation for the TFI conversion, and to investigate the possibility of splitting the huge loom into smaller application specific bundles. Additionally, the loom had melted (exhaust gas from a broken air injector fitting) and wires were damaged. Some wires had been replaced, but some were either melted together, had bare copper exposed, or were covered with random chunks of melted plastic. The feed from the ignition module to the coil (green w/white strip) was fused together with two other wires.

The wiring is not as terrifying as I had feared, and the wires are easily falling into three or four categories. Some wires are tangled, but I think I'll be able to sort it out. Below, you can see as I trace the ignition wires, and isolate the very long red and brown resistance wires. I'm assuming they are a specific (long) length in order to introduce the correct resistance into the system. The brown wire must be 8-10 feet long, and was doubled back in the loom a number of times.

The TFI upgrade uses parts from an '84 F350 with a 460 CDI V-8. Lots of Fords use this ignition system, so why a 460 engine? I assume it so that you can buy pre-assembled spark plug wires. Supposedly, the wires from a Ford 460 fit our AMC 360 good enough. For the best possible fit, "Universal" wires (assembly required), are also an option. On the advice of a few others, I decided to purchase the "custom fit" MSD 8.5mm Super Conductor (MSD-31189). I've never assembled spark plug wires before, but it wasn't too difficult.

The heartburn for me was making sure the wire layout was correct before cutting. You get one chance to cut them! Too long is a problem, and too short... well, that's worse. I created a couple of plastic wire separators to get the wire paths just right. After cutting the wires to length, assembly is pretty easy. You've got to be careful and follow the directions, plus use your noodle. Overall, it was no problem. I took a deviation from the written instructions (that's a nice way of saying the instructions were wrong). They say to cut too much insulation from the wire at the cap end. The included mini-crimp tool, apparently, doesn't work quite right, so there's some easy custom bending that needs to be done to the terminals before the final crimp.

Make sure you get some dielectric grease. It's primary purpose is to make a good electrical seal at the wire ends, but it's also a lubricant. It's not easy to assemble or install/uninstall the wires without the grease. In fact, I've broken wires because the boot was stuck on the plug or cap. Anyway, get some dielectric grease (MSD-8804). Radio Shack and NAPA has it, too.

TFI coil installed, but not wired in. The TFI cap and wires installed. Nearly finished.

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