What is a Chevy 350 block made of?
The classic Chevy 350 small-block block is made of cast iron.
In practice, materials used for 350-blocks vary by generation and model. The traditional small-blocks use gray cast iron, while modern iterations in the Chevy lineup (notably some LS-series engines) and certain aftermarket builds employ aluminum blocks to reduce weight.
Traditional small-block 350: cast iron
When people refer to the Chevy 350, they usually mean the classic small-block introduced in the 1950s and produced through much of the late 20th century. Those blocks are almost exclusively gray cast iron, chosen for durability, machinability, and cost. The iron block handles displacement, heat, and high-compression setups typical of performance use in the era.
Materials used in Chevy 350 blocks over the years, at a glance:
- Gray cast iron block (the standard, most common configuration for the traditional 350 small-block).
- Aluminum block (used in select modern 350-class engines such as some LS-family variants and many aftermarket builds; lighter weight but more expensive and requires different cooling and lubrication considerations).
In practice, that material choice defines weight, performance, and repair considerations for restorers, racers, and hot-rod enthusiasts.
Aluminum blocks in newer 350-family engines
Some Chevrolet 350-class engines in recent years, particularly within the LS family, use aluminum blocks to save weight and improve efficiency. These blocks are a departure from the traditional iron 350 blocks and come with different maintenance needs, heat management, and compatibility considerations with parts such as cylinder heads and intake manifolds.
Summary
For the iconic Chevy 350 small-block, cast iron is the standard material. Aluminum blocks appear in modern or high-performance variants (especially within the broader LS-family offerings and aftermarket builds). Weight, strength, and cost drive the choice, and builders should align block material with intended use and maintenance capabilities.
