Cometic MLS Head Gasket for LS/VTEC

Cometic MLS Head Gasket for LS/VTEC (85mm Bore)

An LS/VTEC build takes the tall, torquey non-VTEC B18A, B18B, or B20 bottom end and puts a VTEC head from a B16A, B16B, B17A, or B18C on top. You get the displacement of the big block and the high-RPM breathing of a VTEC head. It's one of the best-known Honda hybrids for a reason. But the head and block were never made to go together, and the head gasket is what seals that joint. It has to match the bore size of the block, line up with both the head's and the block's coolant and oil passages, and hold up to the compression these builds usually run.

This Cometic gasket is made for that exact combination. It's a three-layer stainless MLS gasket with an 85mm bore, sized to cover a B20's 84mm bore with room to spare. It also works on a B18A or B18B block, either stock or overbored. If you're doing an LS/VTEC, this is a good choice for the head gasket. Just remember it's one part of the swap. Most LS/VTEC builds also need an oil feed for the VTEC solenoid, a timing belt tensioner setup that works with both the block and head, and a tune.

Thickness Sets Your Compression

B18A, B18B, and B20 blocks all have a taller deck than the B16A and B18C engines these heads came from. That changes compression, and head gasket thickness is one of the main ways to adjust it. A thinner gasket raises compression and tightens quench, the narrow gap between the piston and head at top dead center that helps the engine resist knock. A thicker gasket lowers compression. B20 pistons with a VTEC head can end up with very high compression, while a stock B18B usually ends up lower. Pick the gasket thickness based on your pistons, your fuel, and whether there's boost in the plan. Run the numbers before you order.

How the MLS Layers Seal

The two outer stainless layers are embossed with raised beads around each cylinder and passage. When you torque the head down, those beads flatten like springs and press back against the head and block. That spring-back keeps the seal tight as the aluminum head and block grow and shift with heat. The outer layers are coated in Viton, a fluoroelastomer rubber rated to 482°F (250°C), which fills small surface imperfections. Between them is a plain stainless shim that sets the gasket's overall thickness. Because the gasket clamps evenly across the whole surface, the cylinders stay rounder when the head's torqued down. It also doesn't need to be re-torqued after the first heat cycle.

Install Notes

MLS gaskets need flat, smooth surfaces. That matters even more on an LS/VTEC, where the head and block may both be used parts from different engines. Have a machine shop check both for flatness and resurface them to Cometic's MLS surface finish spec if needed. Clean both surfaces down to bare metal, install the gasket dry, and torque the head to spec in the correct sequence. For a boosted or high-compression build, use head studs instead of the factory bolts. Before final assembly, check piston-to-valve clearance with your cams, since the deck height and gasket thickness both change it.

Fitment

• Block: Honda B18A, B18B, or B20
• Head: Honda B16A, B16B, B17A, or B18C (VTEC)
• LS/VTEC hybrid builds in Honda Civic, CRX, and Acura Integra chassis
• 85mm gasket bore: for a B20 (84mm stock) or an overbored B18A/B18B