{"product_id":"manley-chevrolet-big-block-exhaust-valve-kit-1-940in-head-dia-6-400in-o-a-length-0-3415in-stem","title":"Manley Performance Exhaust Valve Kit - 1.940in Head Dia. 6.400in O\/A Length, 0.3415in Stem fits Chevrolet Big Block","description":"Manley Severe Duty® Valves deliver the ultimate in strength, reliability, and high-performance durability. Engineered for extreme gasoline engine temperatures, these valves are crafted from exclusive materials (XH-428 for exhaust and NK-844 for intake), offering unmatched tensile strength compared to competitive alloys. In fatigue testing at 40,000 psi and 1400°F, Manley exhaust valves endured 100 million cycles, while competitors failed after just 100,000, proving a 1,000× longer fatigue life. Each valve features chrome stems, hard tips, and swirl-polished underheads with fully machined combustion faces for superior airflow, efficiency, and wear resistance. Built for those who demand race-winning strength and precision, Manley Severe Duty® Valves set the industry standard for performance and endurance.","brand":"Manley Performance","offers":[{"title":"Default Title","offer_id":44465754177743,"sku":"MAN11583-8","price":301.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0549\/4164\/7055\/files\/Manley-Chevrolet-Big-Block-Exhaust-Valve-Kit-1940i-1758632385.webp?v=1758632386","url":"https:\/\/www.cimotorsports.com\/products\/manley-chevrolet-big-block-exhaust-valve-kit-1-940in-head-dia-6-400in-o-a-length-0-3415in-stem","provider":"CI Motorsports","version":"1.0","type":"link"}