What makes these valves 'Extreme Duty'?

These valves are constructed from NK-844 material, which has significantly higher tensile strength at high temperatures compared to many other valve materials. They have also passed rigorous fatigue testing, enduring up to 100 million cycles under extreme stress and heat.

What is the benefit of the swirl-polished under-head area?

The swirl-polished design on the underside of the valve head helps to improve airflow into the combustion chamber. This can contribute to better engine efficiency and performance.

Does this set include exhaust valves as well?

No, this is a set of eight intake valves only. Manley also offers separate exhaust valves, often made from different materials like XH-428, designed to withstand the higher temperatures and stresses of exhaust flow.

Specifications

Brand: Manley Performance
Part #: 11784-8
UPC: 807298043340

Manley Big Block Chevrolet Extreme Duty Intake Valve 2.3in. Head Dia / .3415in. Stem Dia - Set of 8

Name: Manley Big Block Chevrolet Extreme Duty Intake Valve 2.3in. Head Dia / .3415in. Stem Dia - Set of 8
Brand: Manley Performance
SKU: manley-performance-manley-big-block-chevrolet-extreme-duty-intake-valve-2-3in-he-t14-426874
Price: 361.47 USD
Availability: BackOrder

$361.47

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Manley Big Block Chevrolet Extreme Duty Intake Valve. Set of 8, 2.3" head dia, .3415" stem dia. Built for high-temp gasoline engines.

Key Features

Set of 8 Manley Extreme Duty Intake Valves for Big Block Chevrolet engines.
Constructed from NK-844 material for superior high-temperature tensile strength.
Features a 2.3-inch head diameter and a .3415-inch stem diameter.
Designed for high-temperature gasoline engines.
Chrome stems and hard tips enhance durability and longevity.
Swirl-polished under-head areas and machined combustion faces improve airflow.

⚠️ CA WARNING: This product can expose you to chemicals known to the State of California to cause cancer and/or birth defects or other reproductive harm. Learn more

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About this part

Product Details

These Manley Big Block Chevrolet intake valves are made from NK-844 material, which offers over four times the ultimate tensile strength of competing intake valve materials at 1000°F. This makes them a solid option for high-temperature gasoline engines where reliability under stress is key. The 2.3-inch head diameter and .3415-inch stem diameter are specific dimensions for Big Block Chevrolet applications, ensuring they are sized correctly for the intended engine build.

Manley's Severe Duty? valves are built to last, even under demanding conditions. They've undergone rigorous fatigue testing, enduring up to 100 million cycles at 40,000 psi and 1400°F, which is significantly more than many competitor valves. The chrome stems and hard tips add to their durability, while the swirl-polished under-head areas and fully machined combustion faces help improve airflow and combustion efficiency. This attention to detail in materials and design means you're getting a well-built component designed for performance and longevity.

This set includes eight intake valves, ready to be installed in your Big Block Chevrolet engine. If you're rebuilding the top end of a high-performance or racing engine, these valves are designed to handle the heat and stress associated with those applications.