Cometic MLS Head Gasket for 88-95 Honda Civic SOHC ZC

Cometic MLS Head Gasket, 75.5mm Bore, .030in - 1988-1995 Honda Civic (SOHC ZC)

Most D-series head gaskets don't fail because the engine is old. They fail because of boost. A small D-series turbo build can run cylinder pressures well beyond what Honda planned for, and the factory-style composite gasket is the first thing to give out. Usually it starts with a little detonation on a hot day. The fire ring around one cylinder gets pushed out of shape, combustion gas leaks into the cooling system, and you start finding air bubbles in the radiator and coolant missing from the overflow. Once that seal's damaged, it won't fix itself. You're pulling the head again.

Cometic's MLS gasket uses three layers of stainless steel to keep that seal under pressure. It's .030in thick with a 75.5mm bore, just over the D-series' 75mm stock bore. If your SOHC ZC is getting boost, more compression, or just a rebuild where you don't want to do the head gasket twice, this is a smart gasket to use. On a stock engine that's never going to see boost, a quality composite gasket will do the job for less money.

Steel Layers Instead of Composite

A composite gasket is a fiber sheet with metal rings around the cylinders. It seals well at first, but it compresses and settles over time, and under high cylinder pressure the fire rings can be pushed out of position. An MLS gasket is made from stainless steel. The two outer layers have raised beads stamped around every cylinder and passage, and those beads act like springs. They press against the head and block and keep pushing as the aluminum grows and shrinks with heat. A coating of Viton, a fluoroelastomer rubber rated to 482°F (250°C), fills in small flaws on the surfaces. The plain stainless center layer sets the thickness, .030in here.

Bore and Thickness

The 75.5mm gasket bore gives the gasket half a millimeter of clearance over a stock 75mm bore, so the gasket edge stays out of the flame. It works on a stock block or one with a very small overbore. If your block has been bored out to 75.5mm or more, you'll need a gasket with a bigger bore. The .030in thickness sets how high the head sits on the block, and that affects your compression ratio and quench. Factor it into your compression math, along with your pistons and head.

Install Notes

MLS gaskets seal against metal, not against a soft gasket face, so the head and block both need to be flat and smooth. Have a machine shop check both and resurface them to Cometic's MLS finish spec if needed. That's especially true if the old gasket failed from overheating, which can warp the head. Clean both surfaces down to bare metal, install the gasket dry, and torque the head in sequence to spec. It won't need re-torquing after the first heat cycle. On a turbo D-series, head studs are worth the money. Factory bolts stretch, and the clamp load drops off over time.

Fitment

• 1988-1995 Honda Civic with SOHC ZC engine
• 75.5mm gasket bore: for a stock 75mm bore or a very small overbore
• .030in compressed thickness