Chevrolet
Series M Copper-Cooled (1923)

Why it matters

The Series M was a Chevrolet built around an air-cooled engine concept by Charles Kettering. Overheating and detonation in production engines led to a recall, and it was Chevrolet's last air-cooled attempt for nearly forty years.

How rare is it?

Six separate kinds of rarity – never combined into one number.

Each kind of rarity is rated separately and never combined.

History

Charles Kettering, who had devised the electric self-starter, turned to an air-cooled engine in the early 1920s. He exhibited the Copper-Cooled engine at the New York Auto Show in January, saying it would eventually replace water cooling. The engine displaced 135 cubic inches and was cooled by U-shaped copper fins bonded to separately cast cylinders.

The Series M wore the same body as the water-cooled Superior B, which was essentially an upgraded 490. It weighed about 215 pounds less and was priced about $200 higher, with new prices of $695 to $1,060.

Uneven air distribution made production engines overheat badly and suffer severe detonation, and power fell sharply when hot. Production stopped after 500 cars, and nearly all were recalled.

Technical specifications

Engine

Transmission & drivetrain

Chassis, body & dimensions

Performance

“Not yet verified” means no source has been checked for that value yet. Nothing is estimated to fill a gap.

Sources

Each number links to the exact facts it supports.

1. 1
   1923 Chevrolet Series M Copper-Cooled Level C Auto Editors of Consumer Guide · HowStuffWorks (Consumer Guide Auto Editors) · 2007-08-04

   • it displaced only 135 cubic inches
   • yielded 22 horsepower (at 1,750 rpm)
   • 1,700 (approx.)

   Accessed 2026-11-13