Cometic MLS-5 Head Gasket for B16 B17 B18C (81mm .080)

Cometic MLS-5 Head Gasket for B-Series VTEC - Part #C4231-080

This is not the gasket for a stock rebuild. At .080 inch thick, right around 2mm, this is the gasket you reach for when a boosted B-series needs its static compression pulled down, or when the pistons sit proud of the deck and the head needs room to live. If that describes your build, this one part number solves two problems at once.

What It Is and Why It Works

Cometic builds the C4231-080 as a five-layer MLS: embossed Viton-coated stainless outer layers around stacked stainless center shims that make up the extra thickness. The extra layers are what let a gasket this thick still seal like a thin one, since each stainless layer springs back with every heat cycle and the embossments keep clamp load even across the deck. The Viton coating is heat resistant to 482F, no sealant is needed, and no re-torque is required after installation. A thicker gasket moves the head away from the block, which drops static compression and opens up piston-to-head clearance, exactly what a turbo build on stock-style pistons or a block with pistons popping out of the deck needs.

Specs

Fitment

Covers the DOHC VTEC B-series family at the stock 81mm bore, including JDM B16A, B16B, and B18C variants. Non-VTEC B18A/B18B engines use a different gasket.

What to Know Before You Buy

Do the math before you order. Going from a stock-thickness gasket to .080 lowers compression and widens quench, which is the point on a high-boost build but works against a naturally aspirated one. If the head is coming off for a normal refresh, Cometic's .030 versions of this same gasket family are the right call, and we can get any of them. The 81mm bore matches a stock block; if the engine has been bored, size up the fire ring accordingly. Run head studs with a gasket this thick, torque them with ARP Ultra Torque, and check valvetrain geometry since the head now sits about .050 higher than stock.