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.

What is the difference between TR13 and TR15 valve stems?

The main difference is that a TR13 valve stem fits a smaller rim hole (0.453" or 11.5mm), while a TR15 valve stem fits a larger rim hole (0.625" or 16mm). TR13 is common on passenger, lawn & garden, and light utility applications, while TR15 is typically found on tractor, agricultural, and some older vehicles. A TR15 stem has a thicker base, and an adapter can be used to fit a TR13 stem into a TR15 hole if needed. 
TR13 vs. TR15 valve stems

Feature	TR13	TR15
Rim Hole Diameter	0.453" (11.5mm)	0.625" (16mm)
Base	Thinner base	Thicker base
Common Applications	Lawn and garden, passenger, light truck, universal tubes	Agricultural, tractor, and some older vehicle wheels
Adapter Availability	Can be adapted to fit a TR15 hole using a special bushing	Can be adapted to fit a TR13 hole using a special bushing

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What is the standard valve stem size?

The standard valve stem size for most passenger cars and light trucks is a 0.453-inch (11.5mm) diameter that fits a corresponding rim hole. However, a larger 0.625-inch (16mm) diameter is used for high-pressure commercial vehicles like heavy-duty trucks, tractors, and some older cars, and is often made of metal.
 
Standard passenger car valve stem

• Rim hole diameter: 0.453 inches (11.5mm)
• Max inflation pressure: Up to 65 PSI
• Common models: TR413, TR414
• Materials: Often made of durable EPDM rubber or metal 

High-pressure valve stem

• Rim hole diameter: 0.625 inches (16mm)
• Max inflation pressure: Up to 100 PSI or higher
• Common models: TR600HP
• Materials: Typically a heavy-duty metal construction 

What size valve stem is a golf cart?

Most golf carts use standard snap-in valve stems with a 0.453-inch (11.5mm) rim hole diameter, such as the TR412 for tubeless tires or, in some cases, the TR13 for inner tubes. For carts with inner tubes, a specific tube with the appropriate stem (like a TR13 or TR6) may be required. 
Common sizes and types

• TR412: This is the most common snap-in rubber valve stem for tubeless tires, designed for the standard 0.453-inch (11.5mm) rim hole found on most golf carts. 
• TR13: This is a type of valve stem often used with inner tubes. A TR13 stem is designed to fit a 0.453-inch rim hole, but since it is a separate piece inside the tire, you will need an inner tube with this specific stem. 
• TR6: Some older or different types of golf carts, especially those using inner tubes, may use a TR6 metal valve stem, which is compatible with a smaller, 8mm rim hole. 

How to ensure you get the right one

• Check the rim hole diameter: Measure the hole in your rim. The vast majority will be 0.453 inches (11.5mm). 
• Inspect the current valve stem: Look at the existing valve stem to see if it's a snap-in style or if it's attached to an inner tube. 
• Look at the inner tube (if applicable): If you have an inner tube, check its specifications for the valve stem type it uses, such as TR13 or TR6. 
• Consult your owner's manual or a professional: If you're unsure, your golf cart's manual or a tire professional can help you identify the correct size and type.

What is the stock length of SBC valves?

Stock SBC (Small Block Chevrolet) valve length varies between the intake and exhaust valves, with a common overall length around 4.905" to 4.930" for intake valves and 4.923" to 4.925" for exhaust valves. The precise length depends on the specific engine and the valve type. For example, a set of stock-style valves with 1.94" intake and 1.50" exhaust heads might have intake valves at approximately 4.880" and exhaust valves at 4.923". 
Approximate stock SBC valve lengths

Valve Type	Approximate Overall Length
Intake	4.905" to 4.930"
Exhaust	4.923" to 4.925"

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Example measurements

• Example 1: A set of 1.94" intake and 1.50" exhaust stock-style valves is listed with intake lengths of 4.880" and exhaust lengths of 4.923". 
• Example 2: Another source lists stock-length intake valves with an overall length of 4.930". 
• Example 3: A different set of stock valves lists intake lengths of 4.905" and exhaust lengths of 4.905".