1986 Buick Grand National Aluminum Exhaust Header Gasket

Do I need to clean the mounting surfaces before installing this gasket?

Yes. Clean both the header and manifold mating surfaces with a wire brush to remove carbon buildup and old gasket residue. A clean, flat surface ensures a proper seal and prevents exhaust leaks.

Will this gasket work with a stock manifold or only with an aftermarket header?

This gasket is designed for header applications. If you're running stock manifold setup, verify your port pattern matches before ordering. Confirm bolt hole spacing and port diameter align with your specific configuration.

What's the return process if the gasket doesn't fit once I receive it?

Contact ModSupply customer service with photos of the gasket against your header or manifold ports. Most fitment issues can be resolved with verification before installation. Keep the gasket in original condition for fastest resolution.