Alfred Sloan once wrote in a letter to General Motors stockholders: "The quickest way to profit is to serve the customer in ways the customer wants to be served." A dramatic engine innovation at Chevrolet in 1929 proved his point.
Sloan knew performance and value mattered. Prodded by Chevrolet's aggressive boss, William Knudsen, engineers hit a home run with their new six-cylinder powerplant. During its years of production and decades of faithful service, the engine came to be known as the "cast iron wonder" and the "stove bolt six."
It was the industry's first mass-produced overhead-valve six-cylinder engine. Before 1929, four-cylinder engines powered Chevrolets. The new and more powerful six helped GM capture more than 40 percent of the U.S. market by 1931, up from 14 percent in 1921.
Ford countered with its flathead V-8 in 1932. It took Dodge until 1933 to build a modern six-cylinder of its own.
Success came easily to Chevrolet's 1929 all-iron 194-cubic-inch (3.2-liter) six-cylinder. New iron casting techniques made the engine economical to build. Chevrolet held the line on prices in 1929, which supported a marketing campaign heralding "a six for the price of a four."
Inline sixes were, and remain, smoother-running than four-cylinder engines. For customers of the day, the increase in smoothness was dramatic. And the engine delivered 46 hp, 9 more than the four-cylinder.
Chevrolet literature told customers to expect 20 mpg. Testimonial letters touted even better fuel economy, upwards of 25 mpg.
The six's newfound power and efficiency stemmed from engineering innovations in the cylinder head. Unlike valve-in-block engine designs of the time, the new engine's intake and exhaust valves were in the head, a layout that remains the standard today. The combustion chambers also were integrated into the bolt-on head assembly.
Additionally, the combustion chamber was shaped like a capital "L." Placing the spark plug away from the main area of the combustion chamber at the top of the "L" helped prevent "thump" -- what consumers recognized as pre-detonation, or "pinging."
Improvements in durability came from using forged, rather than cast, connecting rods and crankshafts. These components allowed Chevrolet to upgrade its 1928 1-ton pickup to 11/2 tons for 1929.
Providing insight into the engine's "stove bolt six" moniker, the engine used 1/4-inch bolts to fasten the iron head to the iron block. The bolts and bolt pattern reminded drivers and mechanics of the bolts on cast iron wood-burning stoves, a feature still popular in homes of the day, especially in the country.
The cast iron wonder served Chevrolet well through 1936, when the second-generation six-cylinder made its debut.