{"product_id":"manley-12361-8","title":"Manley 12361-8 - Chevy L83 5.3L 1.560in Head Diameter Pro Flo\/Severe Duty Exhaust Valve (Set of 8)","description":"\u003cp\u003eManley 12361-8 - Chevy L83 5.3L 1.560in Head Diameter Pro Flo\/Severe Duty Exhaust Valve (Set of 8)\u003c\/p\u003e\u003cp\u003eManley Valve - Exhaust, Valve-S\/D L83 53L 1.560, .3136 STEM\u003c\/p\u003e\u003cp\u003eManley 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.\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eProven fatigue strength for extreme performance\u003c\/li\u003e\n\u003cli\u003eChrome stems and hard tips enhance durability\u003c\/li\u003e\n\u003cli\u003eExotic alloys for superior tensile strength, reliability, and longevity\u003c\/li\u003e\n\u003cli\u003eSwirl polishing and machined faces improved airflow\/optimized efficiency\u003c\/li\u003e\n\u003c\/ul\u003e\u003cdiv\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eEngine\u003c\/strong\u003e: \u003cspan\u003e5.3L L83\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eProduct Market\u003c\/strong\u003e: \u003cspan\u003eDomestic\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eHead Diameter\u003c\/strong\u003e: \u003cspan\u003e1.560\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eValve Head Diameter\u003c\/strong\u003e: \u003cspan\u003e1.560\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eStem Diameter\u003c\/strong\u003e: \u003cspan\u003e0.3136\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eValve Stem Diameter\u003c\/strong\u003e: \u003cspan\u003e0.3136\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eO\/A Length\u003c\/strong\u003e: \u003cspan\u003e5.208\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eValve Length\u003c\/strong\u003e: \u003cspan\u003e5.208\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eValve Tip Length\u003c\/strong\u003e: \u003cspan\u003e0.160\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eTip Length\u003c\/strong\u003e: \u003cspan\u003e0.160\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eMargin Width\u003c\/strong\u003e: \u003cspan\u003e0.065\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eSeat Width\u003c\/strong\u003e: \u003cspan\u003e0.110\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eTop of Head\u003c\/strong\u003e: \u003cspan\u003e18 Degree Dish\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eValve Head Shape\u003c\/strong\u003e: \u003cspan\u003e18 Degree Dish\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eUnderhead Angle\u003c\/strong\u003e: \u003cspan\u003e25.00\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eUnderhead Radius\u003c\/strong\u003e: \u003cspan\u003e7\/16\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eValve Series\u003c\/strong\u003e: \u003cspan\u003eSevere Duty? 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