What makes these valves 'Severe Duty'?

The 'Severe Duty' designation comes from the advanced NK-844 material used for the intake valves, which has significantly higher tensile strength at high temperatures compared to standard materials. They've also undergone extensive fatigue testing to prove their durability under extreme operating conditions.

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

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 performance and combustion efficiency.

Are these valves suitable for all gasoline engines?

These valves are specifically designed for high-temperature gasoline engines, particularly Chevy Big Block applications. While the materials and construction offer excellent durability, it's important to confirm fitment for your specific engine build.

Specifications

Brand: Manley Performance
Part #: 12340-8

Manley Chevy Big Block 5.6 OA Length Severe Duty Series Intake Valves - Set of 8

Name: Manley Chevy Big Block 5.6 OA Length Severe Duty Series Intake Valves - Set of 8
Brand: Manley Performance
SKU: manley-performance-manley-chevy-big-block-5-6-oa-length-severe-duty-series-intak-t14-872777
Price: 361.47 USD
Availability: BackOrder

$361.47

On Backorder

Order now to reserve yours — we'll ship as soon as stock arrives. Full refund if we're unable to fulfill.

Manley Chevy Big Block Severe Duty Series Intake Valves - Set of 8. Made from NK-844 material for improved high-temperature strength.

Key Features

Set of 8 intake valves for Chevy Big Block engines.
Constructed from NK-844 material, offering superior high-temperature tensile strength.
Features a 2.375-inch head diameter and a 5.6-inch overall length.
Chrome stems and hard tips enhance durability and longevity.
Swirl-polished under-head areas and fully machined combustion faces improve airflow and combustion efficiency.
Proven through rigorous fatigue testing to withstand extreme stress and cycles.

Secure CheckoutFast Shipping631-982-0042

About this part

Product Details

These Manley Severe Duty Series intake valves are made from NK-844 material, which offers over four times the ultimate tensile strength of typical intake valve materials at 1000°F. This makes them a solid choice for high-temperature gasoline engines, especially those built for demanding applications. The valves feature a 2.375-inch head diameter and a 5.6-inch overall length, designed to fit Chevy Big Block engines.

Beyond the advanced material, these valves incorporate chrome stems and hard tips to boost durability and longevity. The under-head areas are swirl polished to help with airflow, and the combustion faces are fully machined to optimize combustion efficiency. Manley has put these valves through rigorous fatigue testing, showing they can endure up to 100 million cycles under extreme stress, which is significantly more than many competing valves.

This set includes eight intake valves, providing what you need for a complete engine build. If you're rebuilding the top end of your Chevy Big Block and need valves that can handle high heat and stress, these Manley Severe Duty valves are a well-built option.