Cometic C9823 Copper Base Gasket Big Twin Thick - 3.8125 1984-Up 010 2-Pack

The Cometic C9823 copper cylinder base gasket is engineered for precision sealing in Harley-Davidson Big Twin engines from 1984 and up. This 2-pack includes two high-performance copper base gaskets designed for builders who demand reliable sealing and precise deck height adjustment.

Key Features:

• 3.8125" (3-13/16") bore diameter for compatibility with oversized Big Twin cylinders
• .010" thickness allows fine-tuning of cylinder deck height and piston-to-head squish clearance
• Solid copper construction provides excellent heat transfer and conformability to deck surface imperfections
• Sold as a 2-pack for complete twin-cylinder installation
• Ideal for performance engine builds and Big Bore applications
• Made in the USA with premium materials

Copper base gaskets are the preferred choice for high-performance and racing applications where precise compression ratio control is critical. The .010" thickness simplifies setup when building performance engines by allowing builders to dial in exact piston-to-head clearances. Compatible with Harley-Davidson Big Twin Evolution, Twin Cam, and Milwaukee-Eight engines using 3.8125" bore cylinders.