Adjustable shocks are a great thing. One minute you can be soft and absorbent over the rocks and trails, the next you can be cranked up to the max for high speed pre-running over the ruts and rocks. As it turns out pre-running can be hard on a stock ignition system. I found this out during a spring trip into the fern covered mountains when some high-speed pre-running fun shook a bug out of the ignition system of my 1978 Jeep CJ-7. Several rounds of testing and troubleshooting yielded no cause and no fix for the ailing sparkless stock Ford Duraspark ignition system. Before spending too much time on it, I decided it was time for an upgrade. Enter the HEI. Why an HEI? The AMC HEI distributors fits the AMC 290, 304, 343, 360, 390, and 401 ci engines. They also make them for the 6 cylinder engine as well. They utilizing the durable and dependable High Energy Ignition (HEI) system pioneered by GM. The HEI distributors incorporate easily found High Energy Ignition replacement parts. They're a durable 1-piece design with the coil and module mounted internally for an easy 1-wire hook-up. Plus by eliminating the stock AMC ballast resistor, more ignition voltage results and you get improved spark that permits a bigger spark plug gap, resulting in more power and reduced plug fouling. What is an HEI and how it compares to the stock Jeep CJ ignition system? When you look at a stock Jeep CJ-7 ignition system, it consists of a few key components. First the starter solenoid provides power. You also have a coil, the distributor, a vacuum advance, a cap and rotor, below the cap and rotor, an induction coil and a star gear that tells the ignition module when to ground the coil, which in turn sends spark to the rotor and out to the spark plugs. All of these main components are in different locations under the hood and a bunch of wires run back and forth to interconnect the components. My Stock Ford Duraspark ignition system had a few minor upgrades. An MSD Blaster Coil built for offroad abuse, a set of aftermarket spark plug wires, quality spark plugs and some new stock parts, those being a new cap and rotor, a new pickup coil under the cap, a new ignition module and solid, soldered wiring. But something failed and to this day, I don't know what it was even though I replaced and tested everything I could think of including all the wires that run back and forth between the components. Of course I didn't pour a lot of time into troubleshooting the old system, I was soon to be acquiring an HEI setup to replace it anyway. I did want to try to figure out what was wrong, just so I knew but gave up after one go around testing or swapping out each component with spares I had around. The HEI ignition system is a bit different. First, everything is contained within and on the distributor itself. A single power supplying wire coming from your starter solenoid / ignition switch is all that is required. Another wire runs from the distributor to your tachometer. It's simple and reliable. With most HEI distributors, parts are readily available with lots of aftermarket options. On the market there are a few sources for HEI ignition systems for the Jeep AMC 360. DUI makes a nice setup for a cost in the $400+ range. I also found one made by CRT Performance for much less. Proform Street/Strip also makes HEI Distributors for the AMC V8 engine. Ultimately I bought one off of ebay from the seller qtip43 who converts GM Style HEI distributors to work with AMC/Jeep V8 engines 290-304-343-360-390-401. I also picked up a Set of HEI spark plug wires made by Live Wires. Here's the description of the HEI by the Ebay seller qtip43 of Sterling Heights, MI, United States. He also has HEI- AMC/JEEP conversion Distributor for 232-258 inline 6 cyl. AMC/JEEP (GM-STYLE) HEI Distributor 290-401

AMC/JEEP distributor conversion for 290-304-343-360-390-401. Eliminate the original unreliable distributor with this 1-wire hook up unit. Features 50,000 volt built in coil, low saturation ignition module, and brass terminal cap. Engine will run much smoother with added throttle response. Unit uses easy to replace GM parts and HEI ignition wires. Also has provision for tach hook up. Each unit tested before shipped. Add $15 for shipping. Here's a breakdown of the GM Style HEI Distributor that was installed on this AMC 360 Jeep engine. Everything in the ignition system is contained within the HEI distributor. All that is necessary is to supply 12 volts to the power plug located under the rectangle sticking out the side of the HEI Distributor. Next to the 12 volt power plug is a place to plug in your tach. Removing the cap from the distributor. Below the top dust cover is the 50,000 volt coil. Below the cap is the rotor. The underside of the cap is similar to the stock cap. Removing the rotor exposes the advance curve precision weights and springs. Below the advance curve weights is the High-Performance low-saturation ignition control module. Vacuum Advance unit.

Wire harness and capacitor

Below the advance curve weights is are inner and outer magnetic star ring. Not sure about the exact naming of them but the inner star ring is attached to the distributor shaft and when the shaft spins, the points in the rings come within hundredths of an inch, telling the ignition module its time to ground the coil to produce a spark. When compared to the stock magnetic trigger, this setup is much more precise.

Live Wires HEI Spark Plug Wires Distributor Gear (in this case for the AMC V8) and oil pump slot at the base of the distributor shaft. The HEI Replaces entirely this old, for the most part, stock ignition system: I also had a MSD Blaster Coil rated for Offroad with an epoxy core. An old Motorcraft distributor, cap and rotor and all the guts of it. In my case I had a few aftermarket parts mixed in including a set of MSD larger than stock wires, 8.5mm I think they were. The 2nd (or third?) Motorcraft ignition module that I've gone through. When these fail, they fail without warning. If you have one of these, it's wise to carry a spare. Below the cap is the rotor. Simple and basic. Removing the rotor exposes the induction coil, or magnetic trigger that has the job of detecting when the star gear on the distributor shaft passes. This in turn tells the ignition module to ground the coil and create spark. I've had these fail where the Jeep would fire up but when the engine got warm, this coil would open up and not work. the engine cooled (or the coil cooled) and it would fire again. What a bitch it was to figure that one out. I had a whole slew of these plugs. 4 or 5 of them with 2 or 3 wires each. These created a maze of wiring running back and forth across the engine bay. When I was troubleshooting, I had to check each wire for continuity and trace each wire through from one side to the other. They're all gone now. 2 wires with the HEI, 12 volts to the HEI and a wire from my tachometer to the HEI. Vacuum Advance. Here's a better idea. On to the HEI Installation