Is it a Big Block or Small Block (1964 - 1990) Engine?
There are three ways:
- A big block measures 14" between the heads at the manifold base,
while a small block measure 12" between the heads at the manifold
- Facing the front of the engine, at the top surface of the timing chain
area, to the left of the oil fill tube, there is a code about 1.5"
high followed by the casting number. A letter indicates a big block, a
number indicates a small block.
- A tell-tell sign is that the big blocks have a little hump in that
area, whereas the small blocks are flat the whole way across.