was used by the Oldsmobile F-Series for one year in 1933 and then reverted to using the 213.3. It used a 3 3/8" bore and 4 1/8" stroke. This 1933 engine was the first Olds to use removable "shell" bearings in lieu of the earlier poured in place babbit bearings. 229.7 The was used by the Oldsmobile F-Series, Oldsmobile Series 60 and Oldsmobile Series 70 between 1937 & 1940 and also GMC in their 1937 & 1938 T-16, F-16, T-16H and F-16H trucks. It used a 3 7/16" bore and 4 1/8" stroke. 216 The was used by Oldsmobile for only one year in 1939 for the 60 series vehicle. It was basically a de-stroked 229.7 and used the same 3 7/16" bore but a 3 7/8" stroke. 238 The 238 was used by the Oldsmobile Series 60 and Oldsmobile Series 70 between 1941 and 1948. It used a 3 1/2" bore and 4 1/8" stroke 257 The 257 was used only by the Oldsmobile 76 during the 1949-50 model years. It used a 3 17/32" and 4 3/8" stroke. These engines were known as the "Big Six" and had this description cast into the cylinder head. See also Oldsmobile Straight-8 engine Oldsmobile V8 engine List of GM engines References Straight-six engines Straight-6