Oldsmobile straight-6 engine

The Oldsmobile straight-6 was the inline six-cylinder automobile engine that Oldsmobile built from 1923 to 1950, a conventional side-valve design made in a succession of capacities and, at some stages, shared with GMC trucks. Across those 27 years there were five basic series, covering 1923 to 1927, 1928 to 1931, 1932 to 1936, 1937 to 1948 and 1949 to 1950. Sizes ran from the 169.3 cubic inch (2.774 litre) engine of the Model 30, with a 2 3/4 inch bore and 4 3/4 inch stroke and 40 horsepower, through the 213, 230 and 238 cubic inch units of the F-Series, Series 60 and Series 70, to the 257 cubic inch (4.21 litre) Big Six used only in the 1949 to 1950 Oldsmobile 76. That Big Six was the last inline six Oldsmobile built, apart from a few late 1960s and early 1970s models that used the overhead-valve Chevrolet Turbo-Thrift engine. It sits between Oldsmobile's early sixes and the straight-8 and Rocket V8 that followed.