Gaskets and Seals› Engine Gaskets and Seals

Cometic Gasket

Cometic Mercury / Chevy Big Block 4.5in Bore .040 inch MLS Head Gasket

$115.59

SKU: C006 C5638-040

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INSTALL DIFFICULTY
DIY PRO SHOP

Easy — 1–2 hours

Description

The Cometic C5638-040 is a Multi-Layer Steel (MLS) head gasket designed for Mercury/Chevy Big Block engines with a 4.5-inch bore and a 0.040-inch thickness. It features outer layers with a Viton rubber coating, offering heat resistance up to 250°C (482°F). This gasket provides maximum sealing performance for high-output engines and does not require sealants.

Cometic MLS gaskets are suitable for applications with aluminum heads to aluminum blocks or aluminum heads to cast iron blocks, effectively withstanding the shearing forces between different materials. The multiple stainless steel layers enhance strength and provide resistance to corrosion and rebound.

Fitment

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Specifications

BrandCometic Gasket
Part NumberC006 C5638-040

Buy with Confidence

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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