Information on Chevy 250 Inline Sixby Rob Wagner
The Chevrolet inline six-cylinder engine was General Motors' basic powerplant for entry-level Chevrolet cars and trucks. It's part of a long line of straight-six engines dating to 1929 that replaced the inline-four version. The 250 made its debut in 1966 and was phased out of passenger cars in 1979 and trucks in 1984.
Chevrolet's inline-six originally made its debut in 1929 with a 194-cubic-inch displacement and was commonly referred to as the "Stovebolt" straight-six because head bolts resembled those on a stove. The Stovebolt served as a template for future straight-sixes. It featured a bore of 3.3125 inches and stroke of 3.75 inches. It generated 50 horsepower.
The Straight-Six Concept
Chevrolet was one of the few automakers to resist the six- and eight-cylinder engines as the primary powerplants for its cars, sticking with the reliable low-cost, but underpowered, straight-four. The straight-six had a single bank of six cylinders configured in a straight line placed on the crankcase. This configuration provided engine balance that minimized engine vibration that plagued early eight-cylinder versions. More important, the configuration resulted in low manufacturing costs.
The straight-six progressively grew in displacement over the years with the 181-, 207 and 235.5-ci versions. The 250 was launched in 1966 cars and trucks with a bore of 3.875 inches and stroke of 3.53 inches, up from the 235's 3.562-inch bore diameter, but shorter than the 235's 3.94-inch stroke. The 250 generated 155 horsepower.
The 250 featured an integrated cylinder head with a one-barrel carburetor. It was the base engine for 1966 to 1979 American passenger cars and 1966 to 1984 American trucks. It equipped the 1968 to 1979 Camaro, the 1969 to 1979 Checker Marathon and the 1968 to 1992 Brazilian Chevrolet Opala.
GM didn't hesitant to employ the 250 in its other range of cars due to the engine's reliability and economical performance. It was the base engine for the 1968 to 1976 Pontiac Firebird, the 1968 to 1970 Pontiac Tempest, the 1968 to 1976 Pontiac LeMans, the 1968 to 1969 Buick Special, the 1968 to 1972 Oldsmobile Cutlass, the 1971 to 1975 Pontiac Ventura and the 1968 to 1971 Buick Skylark. The 250 in all cars were often coupled with the standard two-speed automatic transmission.
Minor variations of the 250 were produced through the 1970s. The L22 250 was produced for the 1967 to 1979 Camaro. The 1978 version, for example, featured a 105-horse 250 generating 190 pound-feet of torque. A separate 250, the LD4, was produced only for 1978 and the LE3 came in 1979 to 1984 cars, both with slightly increased horsepower and torque. The identification letters and numbers of these engines are GM's internal build codes.
Another version of the straight-six, the 292-ci model used for Chevy and GMC trucks, outlasted the 250 until 1990. But the straight-six was doomed since the mid-1970s when GM began experimenting with a new V-6. The 250 stopped production in 1979 and was replaced by GM's 2.8-liter V-6, which was based on the V-8 design, but with two cylinders lopped off the end.
Rob Wagner is a journalist with over 35 years experience reporting and editing for newspapers and magazines. His experience ranges from legal affairs reporting to covering the Middle East. He served stints as a newspaper and magazine editor in Saudi Arabia and the United Arab Emirates. Wagner attended California State University, Los Angeles, and has a degree in journalism.