The Buick straight 6 was an overhead valve (OHV) straight-six cylinder automobile engine manufactured by Buick from 1914 to 1930. Produced in displacements from 191 to 331 cu in (3.1 to 5.4 L), it was initially used exclusively in the Buick Six platform, later in the Buick Master Six and Buick Standard Six. It continued Buick's tradition of almost exclusively using OHV engines since the Model B in 1904. A total of 11 displacement and bore-and-stroke combinations were produced, starting with a 331 cu in (5.4 L) produced from 1914-1916.

The engine was cast with three pairs of siamesed (3x2) cylinders, and combined its starter and generator in a single unit. The 224 cu in (3.7 L) and 242 cu in (4.0 L) versions lacked a cylinder head, with the cylinders and valves combined in a single unit and pistons accessible via the bottom of the unit (colloquially called a "jughead" engine, since the jugs (cylinders) came off with the head). Beginning in 1924 all engines had a removable head. In 1925, Buick dropped its inline-4 cylinder powered Buick Four, replaced by the lower priced Buick Standard Six in 191 cu in (3.1 L) and 207 cu in (3.4 L) displacement through 1928. The high-end Buick Master Six series produced from 1925 to 1928 was a continuation of the earlier 6 cylinder lineup and used the 255 cu in (4.2 L) and 274 cu in (4.5 L) engines. The Buick Straight-8 engine introduced in 1931 replaced the straight 6 in all models upon its debut, and was the basis of the Holden straight-six motor.

References

• Slauson, H. W.; Howard Greene (1926). "Leading American Motor Cars”. Everyman’s Guide to Motor Efficiency. New York: Leslie-Judge Company.