Cometic C9689-HB HD EVO Stock Bore Gasket Set 3.500" Big Twin .040" Head .020" Base

The Cometic C9689-HB is a premium head and base gasket set engineered specifically for Harley-Davidson Evolution Big Twin engines with stock 3.500" bore. This high-performance gasket kit is designed to deliver exceptional sealing and durability in demanding applications.

Kit Includes:

• .040" (40 thousandths) compressed thickness head gaskets
• .020" (20 thousandths) compressed thickness base gaskets
• Multi-Layer Steel (MLS) construction for superior sealing

Key Features:

• Stock bore diameter of 3.500 inches for standard Evolution Big Twin cylinders
• MLS gasket technology provides multiple layers of stainless steel with precision-engineered embossments
• Excellent heat resistance and combustion seal integrity
• Designed to maintain proper deck height and compression ratios
• Eliminates the need for additional sealants or retorquing

Cometic gaskets are manufactured using advanced materials and processes, making them ideal for stock rebuilds, performance applications, and high-compression builds. The precise thickness specifications ensure proper engine geometry and reliable sealing in Harley-Davidson Evolution Big Twin applications.