Small Block Chevy Severe Duty Intake Valves - Set of 8 by Manley Performance
Severe Duty® series valves are Manley's flagship product in the performance and racing industry. No other company in the world offers XH-428 exhaust material or NK-844 intake material, and no other material demonstrates such a clear superiority over anything else available. The ultimate tensile strength of XH-428 at 1500°F is nearly twice that of competitors' EV-8. At 1000°F, Manley NK-844 exhibits more than four times the ultimate tensile strength of the best intake material from competing products.
In addition to the exceptional strength and fatigue characteristics of Manley NK-844, our proprietary intake material demonstrates an incredible ability to resist "necking" fractures. In a high-seal combustion chamber, fuel detonation can actually deform the intake valve and push it up into the port. The effect of this continuous deformation on competing materials is that a necking fracture eventually spreads around the valve, quickly turning into a chipped, pie-shaped piece. Manley NK-844 is the absolute best material for combating catastrophic necking fractures.
Further evidence of the superiority of Manley Severe Duty® valves is evident in our comprehensive fatigue testing. During normal operation without valve float, valves are subjected to 20,000 to 25,000 psi of stress. However, when a valve bounces on the seat, the stress immediately rises to 40,000 to 60,000 psi. Manley exhaust valves (at 40,000 psi and 1400°F) operated up to 100,000,000 cycles, while competitor products failed at 100,000 cycles. This represents a 1000-fold improvement in fatigue life.
Features
- Head Diameter: 2.020"
- Stem Diameter: 0.3415"
- Installed Height: Stock
- O/A Length: 4.911"
- Tip Length: 0.250"
- Underhead Angle/Radius: 10° x 3/8°
- Margin: 0.050"
- Seat Width: 0.080"
- Top: 7° Dish
- NK-844 Stainless Material
- Chrome Stems and Hard Tips
- Swirl Polished and Fully Machined
Benefits
- Superior stainless steel for high-temperature gasoline engines
- 1,000 times better fatigue strength than competitor products
Please note: The images provided are generic and may not be an exact representation of the product you will receive.
Applications
- 2004-2007 Cadillac CTS-V
- 2007-2008 Cadillac Escalade Base
- 2007-2008 Cadillac Escalade ESV Base
- 2008 Cadillac Escalade ESV Platinum
- 2007-2008 Cadillac Escalade EXT Base
- 1998-2002 Chevrolet Camaro Z28
- 1997-2008 Chevrolet Corvette Base
- 2001-2004 Chevrolet Corvette Z06
- 2005-2006 Chevrolet SSR Base
- 2006-2008 Chevrolet Trailblazer SS
- 2007-2008 GMC Yukon Denali
- 2007-2008 GMC Yukon XL 1500 Denali
- 2008 Hummer H2 Base
- 1998-2002 Pontiac Firebird Formula
- 2004-2006 Pontiac GTO Base
What's in the box?
- 8 - Valves
Warranty
- Manley products are sold without warranty due to the nature of their intended use.
Before Ordering
〇 Regarding Import Duties
At Shaftoya Shopping Site, we pay for import duties incurred during import on your behalf, so there will be no additional charges beyond the total amount paid at checkout.
〇 Checking Compatibility
Since our entire product database is based on North American vehicles (USDM), please confirm whether the product can be installed on a Japanese vehicle (JDM) before ordering. (If you are unsure if the listed product is compatible with your vehicle, please feel free to contact us. Our support team will be happy to check for you.)
If you order without verifying compatibility, we cannot accept returns due to incompatibility.
Please note that even if products are sorted by selecting the year, make, and model in the tabs on our top page, it does not necessarily mean they are compatible with Japanese-spec vehicles without modification.
All products have been translated into Japanese using translation software. As there may be confusing expressions, please contact us before ordering if you have any questions.
○ Regarding Shipping
Shipping costs are paid at checkout. Shipping estimates are calculated automatically once you enter your shipping address on the checkout page. For large items such as body parts, there may occasionally be a significant discrepancy between the automatically calculated shipping cost and the actual cost. In such cases, we will contact you individually via email.
All products are generally shipped internationally from our U.S. warehouse. Unlike domestic shipping within Japan, international shipping takes about 7 to 14 days, so please allow plenty of time for your order. If you are in a hurry, please contact us in advance to confirm delivery times. Note that all products are transported by air; they are never shipped by sea freight.
○ Regarding Japanese Vehicle Inspection (Shaken) Compatibility
All products handled by our company are essentially designed and manufactured outside of Japan. Please be aware that they are not compliant with the "Japanese Vehicle Inspection System," and we cannot provide strength calculation documents or similar paperwork for Japanese inspection purposes. Therefore, all parts are sold for the purpose of "use on circuits, private land, or off-public roads," and installation and use are at your own risk.
○ Regarding Warranty
Please check the contents immediately upon delivery. As all products are shipped internationally from outside Japan, there may be shipping damage to the packaging or the product. For items with shipping damage, defective products, or items different from your order, we will handle returns, refunds, or replacements only if you contact us within 7 days of receipt. Please understand that for products sold through our company, warranty-related support will be handled "exclusively through our company." Please note that we do not provide support through other companies or distributors located within Japan.