What makes these valves 'Severe Duty'?

The 'Severe Duty' designation comes from the advanced materials used and the rigorous fatigue testing they undergo. They are built to withstand significantly higher stresses and temperatures than standard valves, offering a much longer service life in demanding engine conditions.

What is the benefit of the XH-428 and NK-844 materials?

These specialized materials provide exceptional tensile strength at high temperatures. XH-428 for exhaust valves is nearly twice as strong as common alternatives at 1500°F, while NK-844 for intake valves is over four times stronger than competitors' best at 1000°F.

Are these valves suitable for a stock engine rebuild?

While these valves are built for extreme durability, they are specifically designed for high-temperature gasoline engines and demanding applications. They are an excellent choice for performance builds or engines that experience higher operating temperatures and stresses than a typical stock setup.

Specifications

Brand: Manley Performance
Part #: 11231-8
UPC: 807298048017

Manley Chevy Small Block Severe Duty Valves (Set of 8)

Name: Manley Chevy Small Block Severe Duty Valves (Set of 8)
Brand: Manley Performance
SKU: manley-performance-manley-chevy-small-block-severe-duty-valves-set-of-8-t14-364317
Price: 349.40 USD
Availability: BackOrder

$349.40

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Manley Chevy Small Block Severe Duty Valves (Set of 8). Built for high-temp gasoline engines with advanced materials for extreme durability.

Key Features

Set includes 8 valves (4 intake, 4 exhaust) for Chevy Small Block engines.
Exhaust valves are made from XH-428 material, known for high tensile strength at elevated temperatures.
Intake valves are constructed from NK-844 material, offering superior tensile strength at high temperatures.
Chrome stems and hard tips enhance overall durability and lifespan.
Swirl-polished under-head areas and machined combustion faces improve airflow and combustion efficiency.
Designed for high-temperature gasoline engines and rigorous use.

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About this part

Product Details

If you're rebuilding the top end of your Chevy small block engine, especially for demanding applications, these Manley Severe Duty valves are a solid choice. They're designed to handle the extra stress and heat that come with performance builds, offering a significant upgrade over stock components. The set includes eight valves, four for intake and four for exhaust, each made from specialized materials to ensure longevity and performance under pressure.

Manley uses XH-428 material for the exhaust valves, which is notably strong at high temperatures, offering nearly double the tensile strength of common alternatives at 1500°F. For the intake valves, they use NK-844 material, which boasts over four times the tensile strength of competing intake valve materials at 1000°F. These materials, combined with chrome stems and hard tips, are put through rigorous fatigue testing. In fact, these valves have shown the ability to withstand up to 100 million cycles in testing, a remarkable improvement over standard valves that might fail after only 100,000 cycles.

Beyond the material strength, these valves feature swirl-polished under-head areas and fully machined combustion faces. This design helps improve airflow into the cylinder and contributes to more efficient combustion. They are specifically made for high-temperature gasoline engines, making them a great option when you need parts that can take a beating and keep performing.