Chevrolet Small Block Severe Duty Exhaust Valves - Set of 8 by Manley Performance
The Severe Duty® series of valves is Manley's flagship product line in the performance and racing industry. No other company in the world offers XH-428 exhaust material or NK-844 intake material. Furthermore, no other material demonstrates such a clear superiority over all others. The ultimate tensile strength of XH-428 at 1500°F is nearly double that of a competitor's EV-8. At 1000°F, Manley NK-844 exhibits over four times the ultimate tensile strength of the best intake material from our competitors.
In addition to the exceptional strength and fatigue characteristics of Manley NK-844, our proprietary intake material demonstrates an incredible ability to resist string fracture. In a high-seal combustion chamber, fuel detonation can actually deform the intake valve and push it into the port. The effect of this continuous deformation on competitor materials eventually causes a string-like fracture to spread around the valve, soon becoming a missing pie-shaped piece. Manley NK-844 is the absolute best material for combating catastrophic string fracture.
Further evidence of the superiority of Manley Severe Duty® valves is clear in our comprehensive fatigue testing. During normal operation without valve float, valves are subjected to 20,000 to 25,000 lbs of stress. However, when the valve bounces on the seat, stress quickly rises to 40,000 to 60,000 lbs. Manley exhaust valves (at 40,000 psi and 1400°F) operated for 100,000,000 (100 million) cycles, whereas the competitor's product failed at 100,000 cycles. This results in a 1000-fold increase in fatigue life.
Features
- Head Diameter: 1.600"
- Stem Diameter: .3110"
- Installation Height: .100" longer
- O/A Length: 5.040"
- Tip Length: 0.290"
- Underhead Angle/Radius: 15° x 1/2"
- Margin: 0.080"
- Seat Width: .100"
- Top: 9° dish
- Chrome stems and hard tips
- Swirl polished and fully machined
- Exhaust material: XH-428
Benefits
- No need for lash caps or wear caps
- Thin stems for increased flow and weight reduction
- Twice the ultimate tensile strength (at 1500°F) of competitor products
- Superior stainless steel for high-temperature gasoline engines
Please note: The images provided are generic and may not be an exact representation of the product you will receive.
Applications
- 1990–1996 Chevrolet Corvette C4
- 1993–1997 Chevrolet Camaro Z28
- 1993–1997 Pontiac Firebird Formula
- 1994–1996 Buick Roadmaster
- 1994–1996 Chevrolet Caprice
- 1994–1996 Chevrolet Impala SS
- 1994–1996 Chevrolet Caprice Wagon
- 1994–1996 Buick Roadmaster Wagon
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 Consumption Tax
At the Shaftoya shopping site, we pay the import consumption tax incurred at the time of import on your behalf, so there will be no additional charges beyond the total amount paid at checkout.
〇 Confirmation of Compatibility
Our entire product database is based on North American vehicles (USDM), so please confirm compatibility with Japanese vehicles (JDM) before ordering. (If you are unsure if the listed product fits your vehicle, please feel free to contact us. Our support team will be happy to look it up for you.)
If you order without confirming compatibility, we cannot accept returns due to incompatibility.
Please note that even if items are sorted by selecting the year, make, and model on our top page tabs, it does not necessarily mean they will fit Japanese model 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 the time of checkout. Shipping estimates are automatically calculated on the checkout page after you enter your shipping address. For large items such as body parts, there may rarely be a significant discrepancy between the automatically calculated shipping cost and the actual cost. In such cases, we will contact you via email individually.
In principle, all products are shipped internationally from our US warehouse. Unlike domestic shipping in Japan, international shipping takes approximately 7 to 14 days, so please order with sufficient time. If you are in a hurry, please contact us in advance to confirm delivery times. All products are transported via air freight; there is no sea freight shipping.
○ Regarding Japanese Vehicle Inspection (Shaken) Compatibility
Please note that all products we handle are designed and manufactured outside of Japan. They are not compliant with "Japanese vehicle inspection standards," and we cannot provide strength calculation documents for Japanese inspection purposes. Therefore, all parts are sold for the purpose of "use on circuits, private land, or off-road," and installation and use are at your own risk.
○ Regarding Warranty
Please check the contents immediately upon arrival. Since all products are shipped internationally from outside Japan, there may be shipping damage to the packaging or products. We will only provide returns, refunds, or replacement items if you contact us within 7 days of receipt regarding products with shipping damage, defective products, or incorrect items. Please note that for products sold through us, all warranty-related support will be handled "exclusively through us." We do not provide support through other companies or agencies located within Japan.