In 1955, Chevrolet unveiled the company's first overhead valve small block V-8 engine. Initially, the small block Chevrolet engine featured 265 cubic inches of displacement. During the 1968 model year, Chevrolet began production of a larger displacement, 350 cubic inch small block engine. The higher performance small block Chevy came about in 1970, which required changes to the internal design in order to accommodate the larger cylinder bores. Identifying whether or not your particular vehicle has a 350 or 400 small block Chevy engine is an easy task, provided you have the correct information.
Open your vehicle's hood and allow the engine to cool, if applicable.
Examine the rear of the engine block, on the driver's side, below the cylinder head to locate the manufacturer's casting numbers. The casting numbers for your engine will be located below the "GM" stamp at the rear of the block. Utilize a flashlight if you have issues reading the casting numbers on the engine block.
Write down the engine block casting numbers on a piece of paper.
Cross-reference the engine block numbers using a suitable chart guide to find out your engines displacement.
