In 1965, there was still one passenger car in the United States that offered a standard L-head engine: the Rambler American. 

The basic L-head engine design—with its valves in the block, not in the head—enjoyed a long and productive life in the Motor City. From the age of the Model T (1909-27) all through the depression years, the L-head (also known as a side-valve abroad and as a flathead in American slang) was by far the industry’s favored layout. There were always other valvetrain configurations, of course, but the popular L-head was simple, rugged, and with its minimal component count, inexpensive to manufacture.

That changed after World War II, when the availability of high-octane gasoline drove the shift to high-compression, overhead-valve engines, led by the Cadillac and Oldsmobile V8s of 1949. (Read about the ’49 Rocket V8 here.)  Soon the entire industry went overhead. From there, a few manufacturers pressed on with flathead engines for their low-priced models (Chrysler through 1959, for example) but by 1965, excluding commercial and industrial engines, there was only one civilian passenger car left in the U.S. auto industry with L-head power: the modest Rambler American.

The ’65 Rambler American’s flathead six, which displaced 195.6 cubic inches and was rated at 90 hp that year, was closely based on the Nash 600 engine introduced way back in 1941. While the artwork above is a bit cartoonish, it nicely illustrates the Nash 600’s key features. There was no intake manifold as such; rather, the intake ports were integrated into the cylinder block and head and the carburetor bolted on top. Meanwhile, the exhaust manifold was simply a stamped steel tube, more or less, that clamped to the side of the block. Though the exhaust tube was prone to corrosion and blowout it was easy enough to replace, and overall, the Nash six was a marvel of simplicity and ruggedness. When Nash was merged with Hudson to become American Motors on May 1, 1954, the little L-head six carried on. From its original displacement of 172.6 cubic inches, it was enlarged to 184 CID in 1953 and 195.6 CID in 1955.

Through all these years, Nash and AMC also offered overhead-valve sixes and V8s, but the L-head six served as the company’s low-price leader, allowing AMC to offer the compact Rambler American at an extremely low price—at times the automaker advertised the lowest-priced car in America. To shave costs even closer to the bone, the L-head ultimately sported a tiny industrial air filter instead of a proper silencer (below). But nothing is forever, and when American Motors introduced a new and advanced 232 CID straight six in 1964, the little flathead’s days were numbered. For 1965, the side-valve six was available only in the Rambler American 220 and 330 series, the company’s most basic and stripped-down models. And then it was gone.