At what cubic inch does an engine go from a small block to a big block?
,, .in the mid 50’s most car makers were producing engines that would later become known as big blocks . in 1955, Chevrolet came along with a 265 cid v8 engine that was called a small block because it had a closer bore spacing arrangement than did Ford or Chrylser ,this allowed the block to be smaller.the engine was cheaper and lighter than the so called big blocks so Ford and Chrysler began producing there own small blocks for there smaller cubic inch displacement engines as well.the small blocks grew in displacement in later years to around 400 cubic inch’s,all three automakers made large displacement small block engines at some point..they continued to produce the big blocks for there 400+ CID engines because they were much stronger blocks and they could be cooled better.so to summerize it is not the cubic inch’s of a engine that determines whether or not it is a big block but the bore spacing,some small blocks were 351 cubic inch’s while some big blocks were only 312 cubic inch’s.
