Big Block Chevy rails are long and rarely perfectly flat once the engine has been apart a few times. This gasket is a soft, low density blend that takes up those imperfections without needing the bolts cranked down, and at 0.312 in. it also buys back a little clearance under a roller rocker.

Mr. Gasket 5863 Ultra-Seal Valve Cover Gaskets Features:

• Fits 1965-2000 Chevrolet 396-572 Mark IV, V and VI Big Block Chevy engines.
• Low density fiber and rubber blend seals minor head imperfections with low clamp force.
• 0.312 in. thickness offers slightly more clearance for roller rockers.
• Suits hard to seal applications.