At the 1965 Oakland Roadster Show, one of the most unusual hot rods on display was Chuck Miller's 1923 T-bucket powered by a Buick Nailhead that appeared to have no distributor.
There was no distributor cap, no bundle of spark plug wires, and no conventional ignition system visible. Instead, a single ignition unit mounted at the front of the engine supplied high voltage through one lead while all eight spark plugs fired continuously whenever the ignition was switched on. When *Hot Rod* magazine published photographs of the car in its June 1965 issue, many readers insisted the setup could not possibly function. Ten months later, the magazine published a follow-up article explaining the system's operation, and the car ultimately received the show's Engineering Award for its innovative design.
The ignition system was known as the Kaehni ignition, based on a design patented by Frank J. Kaehni (U.S. Patent 2,968,296, granted in 1961). Originally developed for the Economy Engine Company of Youngstown, Ohio, which manufactured large stationary natural gas engines for the petroleum industry, the system was adapted for automotive use by engineer Charles Miller. Instead of relying on breaker points, a distributor, and mechanical timing advance, the Kaehni ignition used a solid-state transistorized oscillator operating at approximately 1.2 kHz to trigger an induction coil capable of generating roughly 45,000 volts. Every spark plug received hundreds of sparks per second regardless of piston position, eliminating nearly all moving parts normally associated with an ignition system.
The concept worked because only one cylinder at any given moment contained the correct combination of compressed air and fuel required for combustion. Although all eight spark plugs fired continuously, only the cylinder on its compression stroke could ignite the mixture.
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