Manley GM-Equipped Exhaust Valve Set
Manley Performance is arguably the world's leading manufacturer of performance and racing components. The reason for Manley's overwhelming success is simple: quality. Manley provides the industry's best materials—proprietary materials that no other manufacturer possesses. Manley valve stems are hard-chrome coated to a thickness of 0.0002 inches, rather than the millionths of an inch found elsewhere. Manley's hard valve tips are superior to competitors' "Stellite" puddles, which can crack and erode from the stem. Manley's valve head and underhead profiles have been at the forefront of flow improvement since the late 1960s.
Severe Duty series valves are Manley's flagship products in the performance and racing industry. No other company in the world offers the exhaust valve material XH-428 or the intake valve material NK-844. And no other material demonstrates such a clear advantage. 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 an ultimate tensile strength more than four times that of the best competing intake material. Further evidence of the superiority of Manley Severe Duty valves is clear in their comprehensive fatigue testing. In normal operation without valve float, valves are subjected to 20,000 to 25,000 psi of stress. However, when the 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 (100 million) cycles, while competing products failed at 100,000 cycles. This provides a 1000-fold improvement in fatigue life.
Features
- Superior stainless steel for high-temperature gasoline engines
- Exhaust material XH-428 with double the ultimate tensile strength of competing products (at 1500°F)
- Chrome stems and hard tips
- Swirl polished and fully machined
- Intake valves feature "Pro Flo" shapes for improved flow
Benefits
- Improved engine reliability
Applications
- 1975–1976 Buick Skyhawk
- 1975 Buick Apollo
- 1975–1976 Buick Century
- 1975–1976 Buick Regal
- 1975–1976 Buick LeSabre
- 1975–1976 Buick Skylark
- 1977 Oldsmobile Cutlass
- 1975–1980 Oldsmobile Starfire
- 1977–1979 Oldsmobile Omega
- 1978–1980 Pontiac Grand Prix
- 1976–1980 Pontiac Sunbird
- 1976–1981 Pontiac Firebird
- 1978–1981 Pontiac LeMans
- 1977 Pontiac Ventura
- 1978–1980 Pontiac Phoenix (RWD)
What's in the box?
- 6 - Exhaust Valves
Warranty
- Manley Limited Manufacturer Warranty
Before Ordering
〇 About Import Consumption Tax
At Shaftoya Shopping Site, we pay the import consumption tax incurred at the time of import on your behalf, so there are no additional charges beyond the total amount paid at checkout.
〇 Checking Compatibility
Since all product databases are based on North American vehicles (USDM), please confirm whether they can be installed on Japanese domestic market (JDM) vehicles before ordering. (If you are unsure if a listed product is compatible with your vehicle, please feel free to contact us. Our support team will be happy to look into it for you.)
If you order without confirming compatibility, we cannot accept returns due to incompatibility.
Please note that even if a product is sorted by selecting the year, manufacturer, and vehicle model using the tabs on our top page, it does not necessarily mean it will fit a Japanese model vehicle without modification.
All products are translated into Japanese using translation software. As there may be confusing expressions, please contact us before ordering if you have any questions.
〇 About Shipping
Shipping costs are paid at the time of payment. Shipping estimates are automatically calculated once you enter your shipping address on the checkout page. For large items such as body parts, the actual shipping cost may occasionally differ significantly from the automated calculation. In such cases, we will contact you individually via email.
All products are generally shipped internationally from our U.S. warehouse. Unlike domestic Japanese shipping, international shipping takes about 7 to 14 days, so please order with enough time to spare. If you are in a rush, please contact us in advance to confirm delivery times. All items are transported via air freight. They are not shipped by sea.
〇 About Compliance with Japanese Vehicle Inspection (Shaken)
All products we handle are designed and manufactured outside of Japan. Please note that they do not conform to the "Japanese Vehicle Inspection System," and we cannot provide strength calculation documents for this purpose. Therefore, all parts are sold for "circuit use, private property, or off-road use only," and their installation and use are at your own risk.
〇 About 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 the product itself. Please understand that we will only provide returns, refunds, or replacement products if you contact us within 7 days of receipt regarding items with shipping damage, defective products, or incorrect items. Please note that for products sold through us, warranty support will be handled "exclusively through us." We do not handle support through other companies or distributors located within Japan.