What makes these valves 'Severe Duty'?

These valves are built with special materials like NK-844 for intake, which offers significantly higher tensile strength at high temperatures compared to standard valve materials. They've also passed rigorous fatigue tests, enduring millions of cycles where other valves failed much sooner.

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

The swirl-polished finish on the underside of the valve head helps to smooth the airflow as it enters the combustion chamber. This can lead to improved air-fuel mixture and more efficient combustion.

Does this valve come with any hardware?

This product listing is for a single intake valve. It does not include valve springs, retainers, keepers, or seals. You will need to source those separately if they are not already part of your engine build.

Specifications

Brand: Manley Performance
Part #: 12354H-1

Manley Chevy L-99 Severe Duty Series 2.165in Head Diameter Intake Valve (Single)

Name: Manley Chevy L-99 Severe Duty Series 2.165in Head Diameter Intake Valve (Single)
Brand: Manley Performance
SKU: manley-performance-manley-chevy-l-99-severe-duty-series-2-165in-head-diameter-in-t14-827409
Price: 100.70 USD
Availability: BackOrder

$100.70

On Backorder

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Manley Chevy L-99 Severe Duty Series 2.165in Head Diameter Intake Valve (Single). Built with NK-844 material for high-temp gasoline engines.

Key Features

Fits Chevy L-99 engines.
Intake valve features NK-844 material for high tensile strength at elevated temperatures.
Head diameter measures 2.165 inches.
Stem diameter is 0.3133 inches.
Overall length is 5.200 inches.
Hollow stem design helps reduce overall valve train weight.

⚠️ 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

If you're rebuilding the top end of a high-performance Chevy L-99 engine, especially one that sees a lot of track time or demanding use, you need valves that can handle the heat and stress. These Manley Severe Duty Series intake valves are built for just that. They use a special NK-844 material that has over four times the tensile strength of other leading intake valve materials at high temperatures, meaning they're less likely to bend or fail under pressure.

Beyond the material, these valves are well-made with features like a hollow stem to reduce weight and a swirl-polished under-head area. This polishing helps improve airflow into the cylinder, which can make a difference in how efficiently the engine burns fuel. The stems are also chrome-plated and the tips are hardened, adding extra durability for long-term use. These are single valves, so you'll need to order one for each cylinder you're replacing.