Little Hercules

Cadillac debuted a vertical inline four-cylinder engine in 1905, but a year later, it was still the 10hp single that had launched the company which sold in droves.

Automobile pioneer Henry Martyn Leland is usually credited with designing the engine in 1901 for Oldsmobile (who rejected it) and installing it in a Ford runabout chassis to create the first Cadillac in 1902. But there's a small and vocal contingent that says engineer Alanson P. Brush was responsible, in no small part because he was issued patents on many of the engine's innovative features.

Derived from an earlier Oldsmobile engine and built by Leland & Faulconer, it was a horizontal single, mounted inline and slightly offset to the left under the middle of the initial Model A. The 6.5-horsepower figure given by Cadillac was not only low; it was deliberately under-calculated, giving buyers more than they bargained for, and instantly creating a reputation for value--and power. Early models had a finned tube radiator in front, with an impeller pump for circulation; later models had an improved radiator design but kept the external, shaft-driven pump.

One of Brush's patents was on the engine's distinctive copper water jacket; the cylinder itself was detachable and cast in a proprietary iron alloy. On the end, a detachable combustion chamber topped the five-by-five-inch cylinder and held opposed vertical valves perpendicular to the cylinder. The intake valve is actuated by an external pushrod and rocker, which has another Brush patent, a sliding cam operated via the steering column, providing variable lift and throttle. A half-speed shaft in the crankcase operates the exhaust valve with another external pushrod and rocker.

Advertised brake horsepower increased to 8.5 in 1904, although the two-main-bearing design, 98.2-cu.in. displacement and automatic elastic-stop updraft Cadillac mixer carburetor didn't change. Cadillac introduced a high-powered four in 1905, and by 1906 claimed to be the largest auto manufacturer in the world. The single earned a 10-horsepower rating, which was probably close to its actual output.

In February 1908, three 1907 Model K singles (a 1906 Model K is shown here) competed in and won the Royal Automobile Club (RAC) of England's Dewar Trophy, which rewarded parts interchangeability. They were driven 50 miles, disassembled, key parts mixed up, reassembled and driven a further 500 miles. A broken cotter pin was the only failure reported.

The Cadillac single was produced until 1909, by which time somewhere in the neighborhood of 16,000 cars had been built. The hundreds of smooth-running examples that remain a century later are a testament to an idea that was perfect for its time.