If an engine ever had a theme song, we're sure its high-rpm melody would be The Doors' "Light My Fire." Before this sounds like another ignition story about doubling spark power, ask yourself what the difference is between a capacitive-discharge (CD)and an inductive-discharge (ID) ignition system. The variance between the two might just get you thinking about how your high-performance Chevy's cylinders are firing.
The typical 12-volt vehicular ignition system relies on an inductive-style sparking system to read the engine's timing signal from the distributor and fire the cylinders individually once per engine cycle. This type of ignition system supplies a very hot spark at low rpm, which works well with factory-type engines. In the event that a high-performance engine builder were to increase the cylinder pressure of the engine or begin operating it at a high speed (above 5,000 rpm), the inductive-spark system would diminish. For this reason, many of today's top ignition companies have switched to CD-style ignitions. These systems most commonly use the inductive trigger signal to activate them, but their actual spark is of CD origin. A CD spark is much more intense than an ID spark, and its powerful current can handle spiking cylinder pressures at high rpm.
Still, the one downfall of the CD system is that its energy cycle takes longer to recharge before delivering a fully powered second spark. Since low-rpm action often requires a hot spark when a street engine is placed under a heavy load (2,000 rpm) many of the top ignition companies today introduce multiple CD sparks during low-rpm operation. By providing two minimally powered low-rpm CD sparks at slow engine speeds and one big, powerful spark at high rpm, the CD-style ignition is able to cover the entire rpm operating cycle of most engines.
Another major downfall of the CD ignition is that if it fails for any reason, the entire sparking system is rendered useless and the vehicle will not run. For this reason, Pertronix has entered the high-performance marketplace with its CD Second Strike ignition box, which is designed to supplement inductive-style ignition systems.
The Pertronix Second Strike box comes fully equipped and can be used on various four-cycle engine combinations using ID ignitions. Its Second Strike CD spark can be tuned within a 2- to 8-degree timing range, and the built-in rev limiter is a technological bonus offering random and sequential spark stealing. |  | 
The factory 0.035-inch gap worked well on our mild-performance engine using the factory ID ignition system and an upgraded Pertronix ignition module. When increased cylinder pressure enters the picture, a Second Strike spark is required keep the cylinders firing. |