The Edelbrock #4259 Aluminum Valve Cover is designed especially for the Edelbrock big-block Chevrolet Big Victor Spread-Port CNC 405 cylinder heads #614468, #617569, #618269, #618368 and #614468. These heavy-duty sand cast aluminum valve covers are designed to provide additional clearance to the Jesel rocker arm set-up when used on Edelbrock's Big Victor Spread-Port cylinder heads. No provision for breather hole has been machined to allow for custom plumbing of the crankcase ventilation system.