There are certain things in life we just take for granted, like the sun coming up in the morning, airlines losing our luggage, and a Corvette that will start when we turn the key.
Generally, that's exactly what happens as the stock ignition transfers electrical energy to the spark plug, jumping the gap of the plug with an arc to ignite the fuel and air in the cylinders. But as our cars age, or if we install a more powerful engine, the factory hardware may not be up to the task. Since Project C3 Triple Ex's ignition consisted of antiquated components of questionable vintage, we felt it was time for an upgrade to a more modern electronic system from MSD.
Chances are, if your car's engine is stock, and you keep the OEM ignition system in good condition, it will work just as GM intended. In a car as old as ours, however, the stock setup didn't offer modern conveniences or safety devices such as an engine-saving rev-limiter or multiple-spark discharge. Additionally, the mass-produced components in most Corvettes, especially those as old as, or older, than our C3, are likely worn out. Coils, condensers, and especially distributors have a finite lifespan before needing to be rebuilt or replaced, and the components in our car were definitely past due.
Another reason we'll be upgrading our ignition, to an MSD ignition system, is to ensure we have enough spark to fire the engine in C3 Triple Ex as we perform future performance modifications. Though only a warmed-over 350 at the moment, it'll soon be tweaked for considerably more power, and a full engine swap-to a higher-compression or boosted stroker motor-may also be in the works. Since all of these options increase cylinder pressure, requiring a hotter spark, we wanted an ignition system that not only boosted ignition energy, but also offered a rev limiter in case our right foot gets carried away. Since our C3 came with a mechanically driven factory tachometer, we were happy to see that MSD offers a Pro-Billet distributor with the correct tach drive, made specifically for Corvettes.
Most engine upgrades that add a significant amount of horsepower-such as installing a performance camshaft, raising compression, adding forced induction, or injecting nitrous oxide-raise the pressure inside each cylinder during combustion. As cylinder pressure increases, it takes more ignition energy for the spark to jump the gap of the spark plug, and eventually the factory ignition system can become inadequate.
While converting to factory HEI ignition and adding individual components such as a hotter coil are options, the technology is still decades old and doesn't offer a way to safely limit revs. The MSD ignition is also a clean-burning multiple-spark discharge system below 3,000 rpm, and it offers stable, high-energy ignition all the way up to 12,500 rpm-far higher rpm than a factory system is capable of. Changes to the ignition-timing curve can also be accomplished in just a couple of minutes, using a screwdriver and the included springs and cams.
MSD has a quality product line too long to list, covering ignition systems for everything from street to all-out race vehicles. Since our Stingray will see both street and track duty, we chose the 6AL-2 ignition box with a Blaster HVC coil. The 6AL-2 provides all digital circuitry, along with a two-step rev limiter that uses rotary dials-instead of chips-to set max rpm. The Blaster HVC is designed for sustained high-rpm use, so it works well for a street or road-course car, which we envision our project ultimately becoming.