Manley Chevrolet Small Block Exhaust Valve Kit - 1.625in Head Dia. 5.165in O/A Length, 0.3415in Stem

Manley Performance is well-known for making strong internal engine components, especially for racing applications. This exhaust valve kit is a prime example, built with their Severe Duty? designation for demanding use in Chevrolet Small Block engines. These aren't just any valves; they're crafted from XH-428 material, a special alloy that Manley says is unmatched globally for exhaust valves, offering nearly double the strength at high temperatures compared to other common materials like EV-8.

You'll notice the attention to detail with the chrome stems and hard tips, which add to their durability and help them last longer. The under-head area is swirl-polished and the combustion face is fully machined. This design helps improve airflow into the cylinder and makes for a more efficient burn. Manley put these valves through some serious testing, simulating extreme stress and heat. They reported that these valves endured up to 100 million cycles in tests where other valves failed after only 100,000 cycles, showing a remarkable improvement in fatigue life, especially under bouncing conditions.

This kit includes exhaust valves specifically designed for high-temperature gasoline engines. While this kit is for exhaust valves, Manley also offers intake valves made from their NK-844 material, which is also noted for its superior strength at high temperatures. If you're rebuilding the top end of your Chevrolet Small Block and need reliable exhaust valves that can handle serious heat and stress, these are a solid option.