Edelbrock 601459 Marine Duty Performer RPM 454-0 Chevrolet marine big block aluminum oval port cylinder heads. The Marine Duty Performer RPM heads are black anodized for corrosion resistance and they include heavy duty Inconel 1.89" exhaust valves. Intake valves measure 2.25". Chamber size is 110cc intake port size is 290cc exhaust port size is 110cc Deck thickness is 9/16". Maximum valve lift is .700". Smaller than stock 11/32" valve stems promote excellent flow and lighter valve weight. Made in the USA at Edelbrock's foundry and machined at Edelbrock's manufacturing facility in the USA. Sold with valves only to allow for valve spring choices. Sold As 2 Cylinder Heads Edelbrock 61459 Performer RPM 454-0 Marine Duty Chevrolet big block aluminum cylinder heads 61459 We offer the entire line of Edelbrock Chevrolet big block aluminum cylinder heads. Check them out! We welcome CANADIAN customers! For ordering information, click on "Orders To Canada" at the top left side of this page. PAYMENT METHODS: PayPal, Visa, Mastercard, Discover, American Express, money orders.