12391-ZVD-000 Head Cover Gasket - Overview. The 12391-ZVD-000 Head Cover Gasket is an essential sealing component in Honda marine engine systems. It supports the cylinder head assembly by providing a reliable seal between the cylinder head and valve cover, preventing oil leaks and combustion gas escape. Crafted to exact OEM standards, it ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. Critical sealing function to prevent oil and co