The Stovebolt Site Forums The Shop Area The HiPo Shop define big block

Hy guys, here is the way I understand it, the Chevy "big block" or "W" engine development began in the mid fifties. The first "big block" was the 348 in 1958, this engine was unique in that the deck or head mounting surface was not perpendicular to the bore, and the cylinder head was completely flat, that meant that the combustion chamber was above the piston but in the cylinder block. A larger engine of the same design appeared in the early sixties, a 409, this engine series eventually became as large as a 427, these engines were physically larger than the 283s and 327s of the day. In 1965 another design of "W" engine was released, this was the 396, this engine was a more conventional design in that the top of the block was perpendicular to the bore and the combustion chamber was in the cylinder head. The cylinder head was a unique design with the valve guides at two different angles in the head, this design is sometimes reffered to as "porcupine" or "canted" valve heads. The smallest of this design of "W" engine is the 366, a truck only engine there were also truck only 427 cubic inch engines which had a taller block they used taller four ring pistons. The big block displacements I can think of are, first series 348 and 409, the 1965 and up I believe designated the mark 4 engine 366, 396, 427, 454, 502, and a larger one yet that I can't remember, hope that helps to answer the "big block" question.