With around 200,000 produced, the Lincoln-Zephyr engine is the best-selling V12 in U.S. production history. Let’s take a look inside.

Introduced in 1936, the Lincoln-Zephyr transformed the Lincoln Motor Company into a volume auto manufacturer. The previous Model K sold in the $4000-and-up range, often with exclusive coachbuilt bodies, and consequently in very small numbers. To reach the  mass market, the Lincoln-Zephyr was priced at a mere $1275, and that required, among other things, an engine that was far less costly to produce than the hulking 414 cubic-inch Model K V12. This new engine would have 12 cylinders, upholding the Lincoln brand, but otherwise it was different in every way.

The Zephyr V12, Model H as it was known, has been called a 12-cylinder version of the familiar Ford flathead V8, and that’s not so far off the mark. But a bit surprisingly, credit for the engine’s design goes not to the parent company in Dearborn but to Frank Johnson, Lincoln’s longtime chief engineer. An old hand at the carmaker, he had worked under Henry Leland at Cadillac and Leland-Falcouner before joining Lincoln. While the V12 shares no major components with the Ford V8, it does feature the same basic layout with an L-head valvetrain, twin water pumps, exhaust passages routed through the water jackets in the block, and a front-mounted, dual-coil distributor driven directly from the camshaft (above).

At 3.75 inches, the V12’s stroke was identical to the Ford V8’s, but its bore was a relatively tiny 2.75 inches, yielding 267 cubic inches of displacement. The centerline-crankcase block was cast with the banks opposed 75 degrees rather than the V8’s 90 degrees or the 60 degrees of a typical V12. This produced an asynchronous firing sequence, but it allowed more compact packaging. And with six firing impulses per crankshaft rotation, the engine was judged plenty smooth enough. In its initial state of tune with a single, twin-throat carburetor, the Zephyr produced 110 hp at 3,900 rpm, competitive with Buick, LaSalle, and the Packard 120.

Over the next 12 years of production the Zephyr received periodic refinements, starting with an upgrade to hydraulic valve lifters in 1938. The bore was enlarged to 2.88 inches in 1940, boosting the displacement to 292 CID and the output to 120 hp. In 1942, the aluminum cylinder heads were exchanged for cast iron while that same year, the bore was opened up again to 2.937 and 305 CID (130 hp). However, multiple problems ensued due to the excessively thin cylinder walls, so Lincoln reverted to the 292 CID version in mid-1946. In its final 1948 configuration, the V12 produced 125 hp at 3,600 rpm and 220 lb-ft of torque.

Between 1936 and 1948, around 200,000 Lincolns, Lincoln-Zephyrs, and Lincoln Continentals were produced with the Model H V12—which makes it the best-selling V12 ever produced by the Motor City. However, the engine was not as universally beloved as the numbers might suggest. Early on the V12 developed a reputation for running hot (much like its Ford V8 counterpart) and the crankcase ventilation proved to be indadequate as well. To be fair, the troubles were ironed out in a few years and the engine became a reliable performer. But by 1949, 12 cylinders had become passé.  Lincoln replaced the V12 with a larger and more modern 337 cubic-inch L-head V8 shared with the Ford truck line.