Mark Houlahan
Tech Editor, Mustang Monthly
January 22, 2019

If you’ve been in the classic Mustang hobby for more than about five minutes, you’ve no doubt heard the name Pertronix. The company is a household name in our hobby for its line of Ignitor brand electronic ignition conversion kits for the Mustang’s original points ignition found in the stock distributor. From inline-six and small-block to the big-block Mustangs (and every other Ford or Brand X in your driveway) there’s a Pertronix Ignitor solution available. They’re quick and easy to install, and they are a “set-and-forget” setup with no wearing/moving parts, unlike those old points systems.

As much as we love recommending the Ignitor (and we have one in our ’66 Mustang as well), the Ignitor is simply a “trigger” for the ignition coil. Upgrading the coil—naturally, Pertronix has solutions available for you there too—certainly helps, but for a higher-performing engine package (compression, hotter cam, aftermarket heads, etc.), a full ignition upgrade with more spark energy, a rev limiter, and other features is something to consider. Pertronix has offered ignition “box” solutions in the past, but its latest, the Digital HP, really takes things to the next level in a compact size that fits any engine compartment.

The Digital HP is offered in black and silver case finishes, so you can let it blend in or stand out, depending upon how your engine bay looks. The Digital HP is small (about one third of the size of a traditional ignition box), but it packs a punch with a feature set that’ll help keep your engine safe on the street and the track. The Digital HP provides more than 187 Millijoules of spark energy, and that energy is delivered in multiple sparks all the way to redline. Speaking of redline, the Digital HP keeps your engine in one piece with its three-step digital rev limiter. The rev limiter can function for burnout and/or launch control (via owner supplied momentary switches), as well as for max rpm for engine protection. If your engine requires timing retard for easier starts, the Digital HP has you covered there as well, and it also features an rpm-triggered output (say for a shift light), tachometer output, diagnostic LEDs, and more. Lastly, this little wonder is 50-state legal too!

We grabbed a friend’s ’68 fastback that was already running a Pertronix Ignitor along with a wide-cap adapter kit for this upgrade. We’re going to add the Digital HP in silver along with Pertronix’s Flame-Thrower HP E-core ignition coil and 8mm MagX2 universal plug wire kit. We’ll use Pertronix’s new plug wire stripper and crimper tools to build a custom set of plug wires for the small-block. Take a look and then give Pertronix a shout for your ignition needs.

This is our pal Allen’s ’68 fastback. It’s a clean driver and weekend cruiser with an AOD conversion, nice stance, full exhaust, and a recent top end engine upgrade. With the smaller chamber/higher compression heads, larger intake and carb, etc.¬¬ he was looking for an ignition upgrade over his trusty Pertronix Ignitor and Flame-Thrower coil. We had just the fix for him that wouldn’t “jump out” of his engine bay.
While the original Ignitor under his distributor cap can certainly trigger the Digital HP, the old Flame-Thrower coil wasn’t compatible, so we’re going to remove it for a modern E-core coil upgrade. Allen moved the coil from the intake to the cylinder head when the engine’s intake and carb were added.
While the original Ignitor can usually run safely off of the factory resistance wire, Ignitor II and III must use a 12-volt ignition source, as does the Digital HP ignition. Generally the two options are to bypass the resistor wire under the dash, or use the original coil feed wire to trigger a relay. Pertronix offers just such a relay kit under PN 2001 which makes things easy. Thankfully, Allen’s resistor wire was already bypassed and we were getting a full 12-volts on the coil feed wire for our upgrade.
The Pertronix Flame-Thrower HP ignition coil is an E-core design (not an oil filled canister) and with its mounting bracket it does take up some real estate. Generally we prefer to mount these on the shock tower or inner fender with a longer coil wire, but Allen asked us to minimize any new holes to his sheetmetal. With that in mind we decided to mount it where the old coil was and fab up a simple bracket for it.
Using some scrap steel from our project pile we came up with this. Using the original bolt that held the old coil we’ll mark and drill two holes to secure the coil, hit it with high-temp black paint, and call it good.
Here we have the final mockup of our new coil bracket. Everything fits nice and it’ll keep the coil wire short as well. While the paint is drying we’ll work on mounting the Digital HP and tackle the fairly simple wiring connections for it. Moving on!
There’s no getting around the fact the Digital HP requires a solid mounting surface and mounting holes drilled. We minimized the additional holes by starting with an existing screw hole and securing the ignition to the inner fender apron with it followed by marking the remaining three holes to be drilled out.
The final installation keeps the Digital HP down low and out of sight while still allowing quick access to the diagnostic LEDs and control switches for programming the unit’s many features. If you’re looking to completely hide the Digital HP (which is easy due to its size) you might want to consider the new Digital HP Mobile, which uses a Bluetooth connection to your smart phone or tablet to make programming adjustments instead of the small dials.
We plugged in the automotive-grade wiring connector to the Digital HP and sorted our wiring into three bundles: battery wires, wires going to the coil/engine harness, and wires we wouldn’t be using, and then did a rough routing to determine where we were going to place the wires and their final lengths. Once confirmed, we unplugged the connector until all wiring is completed.
Pertronix now offers two different ratcheting crimper kits. One for wire terminals and spark plug wires (PN T3001) that we’ll be using today, and one for weatherpack-style terminals with terminals and connector shells (PN T3005). These make wire crimping quick and easy with a perfect crimp each time.
Following the instructions’ clear wiring diagrams (it includes several to allow connection to all popular pickup types/distributors, including magnetic pickups) we trimmed our wires to their final length and made our connections for the distributor wiring, ignition feed, and coil wiring using the ratcheting crimper.
We did the same for the direct-to-battery wires as well. Cut them to their final length, crimp terminals on, and connect them directly to the battery positive and negative terminals per the Digital HP instructions. For now we’re simply coiling the unused wires up and tucking them out of the way. If Allen opts to connect a switch to activate the optional rpm limits, etc. in the future they’re ready to be routed and connected. We have a stash of wire sleeving and these cool sleeving tools from our friends at Painless Performance (www.painlessperformance.com) which makes cleaning up the wiring and protecting it a breeze.
Our finished wiring connections at the ignition coil, and just behind it you can see our harness routed up to the intake/distributor for the Ignitor wiring, aftermarket tach wire, and original coil feed wire.
And this is our completed battery connections. All nice and neatly routed, sleeved, and very low key looking, just what the owner asked for.
Once all wiring is completed the Digital HP’s wiring harness can be connected to the ignition box for the final time. Ensure the red lock tab is engaged to prevent the connector from accidentally being disconnected.
To wrap up our Pertronix ignition upgrade we decided to add a set of 8mm MagX2 wires. These wires feature dual current paths, a low 500 ohms per foot resistance, and a heat-resistant silicone outer jacket. Available in black or blue jacket color they include terminals for traditional distributor caps as well as modern “tower” caps like this fastback is using and are cut-to-length for an exact fit. With our Pertronix crimper kit it was simply a matter of switching crimp jaws to the spark plug terminal jaws and we were ready to go!
If you’re firing-order challenged we strongly urge you to replace one wire at a time. However, if you’re comfortable with firing order and wire routing feel free to do more than one wire at a time. We prefer to pull the wires off of one side at a time. Here we’ve replaced the wires for cylinders one through four and are determining final length at the distributor cap. Work from the shortest wires in the kit to the longest, this way you’ll never end up with a plug wire that’s too short.
After cutting the wires to their final length this nifty plug wire stripper from Pertronix (PN T3004) makes quick work of properly stripping the outer layers of the plug wire, leaving just the wire core ready for the addition of the wire terminal. Simply clamp the stripper over the wire, give it a few loops with your finger, and pull it off of the end of the wire.
Using our Pertronix crimper it couldn’t be any easier to make the final terminal installation. What used to be something you had to do in a bench-mounted vice with a pair of crimp jaws you can now complete directly on the car. Simply fold the wire core back over the wire’s outer jacket and place into the terminal to be crimped. This ensures the wire core is directly in contact with the metal terminal.
Using a bit of dielectric grease or in a pinch some silicone spray, lube the plug wire boot and insert the terminal/wire assembly until the terminal is fully seated and square with the boot’s opening. Congratulations, you just built your first plug wire. Only seven more to go (don’t forget the coil wire!).
Seen here is the finished project. Just as the owner requested, nothing really jumps out (no big red ignition box, loose wires routed only with tie wraps, etc.). The black wires look OEM, but work great for the hotter ignition, and the compact size of the Digital HP means it’s tucked out of site. We asked Allen what he wanted for a rev limiter and it turns out the 5,500 rpm default worked, so we literally had to make zero changes to the Digital HP. However, if you wish to increase the rev limiter or make further changes the instructions are very clear on how to make the changes using the setting dials, or as we mentioned earlier, the Digital HP Mobile allows those setting to be made on the fly from the Pertronix app on a smart phone or tablet. What could be easier?

Photography by Mark Houlahan