In the game of air-fuel-spark, the ignition system is often overlooked by builders who get fixated on the numbers. While it’s true that forced induction and advanced fuel system setups can deliver impressive results, ignoring a key component of the internal combustion equation can create serious issues and leave horsepower on the table.
“The ignition system always seems to get neglected,” says Joe Pando of MSD Ignition. “Folks concentrate on the engine combination, and the ignition system ends up being the last thing on the list. People tend to skimp on these components because of that.” But as horsepower levels rise, the limitations of inadequate ignition systems quickly become apparent.
“You might think you can burn everything with a stock ignition, or maybe some small upgrades,” he says. “But the tailpipe will tell you if that’s the case – if the engine isn’t burning fuel efficiently, you’ll smell it in the exhaust. Beyond the emissions concerns that can create, that unburnt fuel means your engine isn’t making the power it’s supposed to. It can also lead to drivability issues, such as poor throttle response, dips in the powerband, and even misfires.”
Here, Pando guides us through a range of ignition system components and upgrades that should be on builders’ radars. Along the way, he offers helpful insights into the types of applications where these upgrades make the most sense.
As with most aspects of performance, a well-sorted ignition system ultimately starts with the fundamentals. After all, sophisticated technology isn’t worth much if it can’t reliably do its job.
“Caps, wires, and rotors are things that always seem to get overlooked,” says Pando. “These are consumable items, and people need to treat them that way. When I talk to customers, I ask how often they change their oil, and they tend to be very religious about doing that – X amount of miles or X amount of runs. But when it comes to things like spark plug wires, it’s, ‘Oh, they’ve been on there for a few years.’ Neglecting this stuff will come back to bite you.”
In terms of maintenance frequency, Pando likens it to other powertrain service schedules.
“Typically, with a purpose-built drag car, I’ll recommend changing the spark plug wires at least twice a year – not every five years! Part of the rationale behind that is that there’s no obvious way to determine when these parts are starting to fail. You can open the hood in a completely dark environment, rev the engine, and you might be able to see the halo and the glow, and maybe an arc here and there.
You can also test the wires with an ohmmeter. That’s something we regularly do at the track. We use a piece of wood with two steel rods sticking out. We connect our meter to those rods and plug the wires in, generating a number. If you move the wire around while doing that, the number shouldn’t change. If it does, it means the conductor is broken, and it’s probably time to replace the wire. But ultimately, it’s better to just treat cap, rotor, and wire replacement as preventative maintenance. These are consumable parts.”
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If you’re working with a vintage engine that uses a points-style distributor, Pando says switching to an electronic replacement, like an MSD Ready-To-Run distributor, can unlock horsepower while also improving the engine’s driving manners and overall reliability.
“Moving from points to an electronic system is definitely a step in the right direction. These distributors are called Ready-To-Run because they only need a coil. They come with a high-energy ignition module inside, so all you need to do is connect the stock coil – or, even better, an aftermarket performance coil – and you’re good to go.”
Along with serving as a solid upgrade for existing vintage engine builds, he also cites this as a particularly attractive option for new crate engines that don’t have ignition components included.
“If you’ve got a combination making, say, 400 to 500 horsepower, this is a great entry-level upgrade. It eliminates the servicing requirements of points, allows for easier engine starts and smoother idling, and offers a ton of timing adjustability. With points, what you see is more or less what you get unless you take it to a specialist for modification. But with an electronic distributor like a Ready-To-Run, you can tailor the timing curve with the included sets of bushings and springs. That’s another thing people tend to overlook, leaving performance on the table. The instructions offer a guide with suggested combinations based on how quickly the advance comes in.”
Pando notes that there are two main types of traditional ignition system designs: inductive and capacitive discharge. While inductive-style systems get the job done in garden-variety applications, capacitive discharge offers several advantages that cannot be replicated with an inductive system.
“Production vehicles were never offered with capacitive discharge systems due to the costs involved. However, inductive ignition systems will always develop less power at high RPMs compared to capacitive discharge systems. With an inductive system, time is working against you. At low RPMs, the time to charge the coil to, say, 80%, isn’t a concern. But as the RPMs increase, the time allotted to charge the coil between combustion events decreases. This becomes a bigger issue when you start modifying engines for more power. When you’re really pushing an inductive system with a high-performance engine, you’ll start to see misfires at those higher RPMs.”
Capacitive discharge systems, on the other hand, are not susceptible to these RPM-based time constraints. “An MSD unit, for example, has two large transistors, a transformer, and a large capacitor in the box. While it might take up some room in the engine bay, that capacitor is able to charge to 100% regardless of the amount of time between combustion events. The spark energy you have at idle is the same energy you’ll have at 10,000+ RPMs.”
For those who want to gain the benefits of a capacitive discharge ignition setup while keeping costs in check, he recommends MSD’s Street Fire Ignition Control unit. “These are very affordable. It’s a discreet, compact unit with features like an adjustable rev limiter. These wire up in the same way as a traditional MSD box, so you can apply it to a points engine, a fuel-injected engine, or a magnetic pickup distributor – it’s very versatile. I run this box in all my vehicles, and it’s perfect for anything under roughly 800 horsepower.”
He also notes that capacitive discharge units like the Street Fire can help address tuning and engine combination issues. “For DIY hot rodders, bigger is always thought of as better. But that means people usually end up with camshafts and carburetors that are too big for the application. To a certain degree, you can mask some of those issues with a capacitive discharge ignition box more effectively than with an inductive setup. If a combination is delivering too much fuel or is too lean, it makes it more difficult for a cylinder to fire. But as you increase the ignition system’s spark energy, the margin for error widens, and you can compensate for those mismatched parts a bit more.”
At power levels beyond 800 horsepower, Pando says that the MSD 6AL ignition control unit’s more sophisticated design and feature set offers a solid upgrade over the Street Fire box. An MSD Pro-Billet distributor is purpose-built for the demands of high-horsepower applications like these.
“When you start pushing big horsepower, a Ready-To-Run distributor isn’t going to match the needs of the engine combination. That’s when it makes sense to step up to a Pro-Billet distributor. The design and materials we use go well beyond what you’ll find in competitors’ products. Almost everything in these distributors is built with chromoly parts. And with a GM-style Pro-Billet distributor, for example, we use a special QPQ plating process on the shaft. Since there isn’t enough material in the housing to put a roller bearing at the bottom, we use a sintered iron bushing. This bushing is extremely hard, so the material going onto it must be hard as well. We also added a roller bearing on top.
And when it comes to the flyweights and pins, most manufacturers silver braze those pieces together, but we TIG weld everything in place, grind the weights, and then QPQ plate everything. These materials and design choices ensure our billet distributors provide durability that outperforms anything else out there.”
As horsepower numbers venture deep into quadruple-digit territory, the strategies for effective ignition control change.
“At a certain power range, you don’t really look to distributors anymore,” says Pando. “With horsepower at this level, parts start to move around more, and just two degrees of timing can make a significant difference in power. Stability becomes a greater concern because the instability caused by that movement can alter timing. In today’s world, half a degree of timing change can be measured in the data and on the time slips. But if you’ve got a distributor moving around, that instability would completely negate any benefit from that half-degree tuning tweak.
So we need a way to get that stability back. A crankshaft connects to a camshaft in one of three ways: by a chain, a belt, or a gear drive. Meanwhile, the reluctor in a distributor is about two inches in diameter, and it’s spun by the camshaft. At engine speed, the parts that connect the crank to the cam will move around, and the camshaft itself will start to twist. All of this affects timing with a distributor. That’s why you see crank triggers in these applications rather than distributors.”
Pando explains that a crank trigger moves the reluctor wheel to the front of the crankshaft to improve timing stability. “Now we don’t have to worry about the movement of those parts as much because we’re putting a large wheel in front of the damper, mounting a bracket on the block, and adding a pickup. Every time the magnet comes around, it tells the ignition system to fire. So regardless of the movement up top, the crankshaft isn’t moving as much as the camshaft anymore. This is how you can realize the benefits of those half-degree timing changes at high power levels.”
If you're still unsure whether a particular ignition system upgrade makes sense for your build, Pando recommends reaching out to MSD directly to get tailored advice.
“Our team still goes to the races. This is a day-in and day-out thing for us.”
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