What size are SBC valve stems?
SBC, or Small Block Chevy, valve stems typically come in two standard sizes: 11/32" and 5/16". The size of the valve stem is an important factor to consider when servicing or replacing components in a Small Block Chevy engine.
What are SBC Valve Stems?
Valve stems are the part of the valve that protrudes through the cylinder head and connects to the valve train components, such as the rocker arms and pushrods. The valve stem size is crucial because it must match the size of the valve guides in the cylinder head, as well as the components that interface with the valve stem, like the valve springs and retainers.
11/32" vs. 5/16" Valve Stems
The two most common valve stem sizes for Small Block Chevy engines are 11/32" and 5/16". 11/32" valve stems are found in earlier Small Block Chevy engines, typically up to the mid-1970s. 5/16" valve stems became more common in later Small Block Chevy engines, starting in the late 1970s and continuing through the end of the Small Block Chevy production run.
The valve stem size is an important consideration when sourcing replacement parts, as the wrong size valve stem can cause issues with proper valve train operation and engine performance.
Identifying Valve Stem Size
- Measure the diameter of the valve stem with a caliper or micrometer to determine the exact size.
- Check the engine's service manual or other documentation to identify the factory-specified valve stem size.
- Inspect the cylinder head to see if the valve guides are stamped with the valve stem size.
Knowing the correct valve stem size is crucial when servicing or rebuilding a Small Block Chevy engine to ensure proper fit and function of the valve train components.
