Mopar engine differences

Short block and long block can mean different things. Short block means an engine with no heads. It might have camshaft, it might not. It totally depends on whose short block it is. It might have oil pump and pan. It might not. It might have timing cover. It might not.

Long block means engine with heads. It might have the complete valve train. It might not. It might have all of the tin like oil pan, timing cover and valve covers. It might not. It's all dependent on what company offers it and how they offer it.

Small block and big block are technically defined by the bore spacing. Chrysler engines are pretty easy to differentiate. Big blocks have distributors in the front, small blocks in the back. Early hemis (51-59) are generally considered small blocks, since their blocks are almost exactly the same size as the A and LA engines, although they are simply referred to as "Hemi".

Second generation Hemis (the 426) are big blocks, since they are based on the Chrysler RB (raised block) engines.