Cometic C9821 HD Copper Base Gasket 3 5/8" Big Twin 84-Up 2-Pack .020"

The Cometic C9821 is a high-performance copper base gasket designed specifically for Harley-Davidson Big Twin engines from 1984 and newer. This gasket features a 3 5/8-inch bore diameter and .020-inch thickness, providing precise combustion sealing for Evolution, Twin Cam, and Milwaukee-Eight engine applications.

Key Features:

• Premium copper construction for superior heat dissipation and conformability
• 3 5/8-inch (3.625") bore diameter for Big Twin cylinders
• .020-inch thickness for precise deck height adjustment
• Sold as a 2-pack for complete V-twin engine coverage
• Heavy-duty design for high-performance and high-compression applications
• Embossed sealing beads ensure exceptional sealing under extreme conditions

Cometic's copper base gaskets are manufactured from high-quality copper material that provides excellent thermal conductivity, helping to transfer heat away from critical sealing areas. The malleable nature of copper allows the gasket to conform to slight imperfections in mating surfaces, creating a reliable seal even in demanding performance environments. These gaskets are ideal for custom builds, engine rebuilds, and performance applications where precise compression ratio tuning is required.