Buick straight-6 engine

The Buick straight-six was an overhead valve inline six-cylinder engine that Buick made from 1914 to 1930, in eleven displacement and bore-and-stroke combinations from 191 to 331 cubic inches. It powered the Buick Six and later the Master Six and Standard Six, and it continued Buick's habit, kept since the Model B of 1904, of using overhead valves almost without exception. The earliest versions had no removable head: the 311 cubic inch engine had its cylinders cast in three siamesed pairs, and the 224 and 242 cubic inch engines had all six in one casting, which earned the nickname jughead engine because the cylinders came off together with the head. From 1924 every engine had a removable head. In 1925 Buick dropped its four-cylinder car in favour of the cheaper Standard Six, and the straight-eight of 1931 replaced the six; that engine was also the basis of the Holden straight-six.