what is meant by a 350 cubic inch engine?

Answer 1

Engine displacement is defined as the total volume of air/fuel mixture an engine can draw in during one complete engine cycle; it is normally stated in cubic centimetres, litres or cubic inches. In a piston engine, this is the volume that is swept as the pistons are moved from top dead centre to bottom dead centre.

http://en.wikipedia.org/wiki/Engine_displacement