Is the Chevy v8 350 a small block or big block?

"The v8 350 is a small block Chevrolet motor.....................it became a big block at 396cubic inches......so anything smaller is a "small" block"

this is a little misleading. a 350 is indeed a small block. a 396 is indeed a big block. but you can have a small block that is (internally..cubic inch wise) actually larger than a big block. for example GM made a 400 cubic inch small block. internally it is a larger engine than a 396, but the outer dimensions of the 396 are larger than the 400 small block. and the external dimensions and cylinder head design are what make a small block a small block, and a big block a big block. a small block engine simply has a physically smaller block...a big block is called a big block because it's block is bigger than that of a small block.