One U.S. auto manufacturer did offer an overhead-cam engine in 1962: Kaiser Jeep, no less. It’s a remarkable design, check it out.

The father of the overhead-cam Jeep Tornado Six was Achille Carlo “Sammy” Sampietro (above), a talented engineer from Lake Como, Italy with a string of accomplishments all over the world. Historian Karl Ludvigsen called him “the thinking man’s engineer.”

Following stints with Alfa Romeo, Railton, Healey, Rootes, and others, Sampietro joined Willys Motors in Toledo, later to become Kaiser Jeep, where he was promoted to chief engineer in 1961.  There, his tasks included somehow modernizing the company’s obsolete 226 CID L-head six, a former Continental engine Willys had inherited from Kaiser Motors in 1953. Portions of its design actually dated back to the Graham-Paige six before World War II.

Sampietro retained the basic architecture of the old Hurricane six on the bottom end, including its quaint undersquare stroke/bore ratio. While the bore was opened up slightly from 3.31 in. to 3.435 in., the stroke remained unchanged at 4.375 in, yielding a stroke/bore ratio of 1.274:1 and a displacement of 230 cubic inches. The major changes were to the cylinder head, an area where Sampietro had a wealth of experience.

The new cylinder head was cast in aluminum with hemispherical combustion chambers and two valves per cylinder with a 70-degree included angle. The compression ratio was bumped from 6.86:1 to 8.5:1, thanks to the more modern combustion chambers, while the aluminum intake manifold supported a Holley 2300 two-barrel carburetor for ample breathing.

A single, centrally located camshaft, chain-driven, operated trendy stamped-steel, ball-mounted rocker arms, a feature pioneered by General Motors. However, there’s one novel feature that the drawing above suggests but doesn’t clearly show. Both the intake and exhaust valves for each cylinder are actuated by a single cam lobe. That is, the camshaft had only six cam lobes (below). While this setup isn’t unique in automotive history, it certainly is uncommon.

Obviously, the goal here was to reduce costs, both in adapting the ancient L-head six and in the creative overhead-cam conversion. As Sampietro told Roger Huntington, writing for the July 1962 issue of Hot Rod magazine, manufacturing cost was increased a mere six percent in the transformation from Hurricane to Tornado. With its improved volumetric efficiency and increased rpm capability, the new engine produced  140 hp at 4,000 rpm with 210 lb-ft of torque at 1,750 rpm. The best the old L-head could do was 105 hp at 3,600 rpm.

Unfortunately, the OHC six didn’t work out for Kaiser Jeep. Intended for the Wagoneer and Gladiator, also new in 1962, the Tornado suffered a number of problems, including excessive oil consumption, possibly due to the company’s meager development resources. For 1965, Jeep civilian vehicles switched to American Motors inline sixes and the former Buick V6, while the military vehicles (Kaiser M715 below) continued on with the Tornado with no better results. However, the cammer did find success with IKA in Argentina, where it remained in production through 1982. But that’s another story.