In its place was a new , all-cast-iron-block V6 with a Rochester 1-barrel carburetor that generated at 4400 rpm. It was almost 30 cu. in. larger than a prior, unrelated V6 introduced for the 1962 model year. The 225 was basically a Buick 300 CID V8 engine, less two cylinders. The basic V8 option was a 300-cubic-inch, with cast-iron-block, aluminum-heads, and a Rochester 2-barrel carburetor that generated at 4600 rpm. A high performance version was offered with 11:1 compression and a 4-barrel carburetor, generating . A long-throw, 4-speed Hurst shifter was available. For the 1965 model, cast-iron blocks and heads were used for all engines.