Cometic C4231-030 Honda B-Series VTEC MLS Head Gasket – 81mm Bore, .030″ Thickness

Technical Specifications

Year, Make, Model and Engine Fitment

These engine families and model ranges are consistent with Cometic’s application information and B-series listings. Verify the specific engine code and bore before ordering, especially on engine-swapped vehicles.

Fitment warning: This is a B-series DOHC VTEC gasket. It should not automatically be substituted for a non-VTEC B18A/B18B gasket or an LS/VTEC hybrid configuration. Cometic offers different gasket part numbers for those applications.

Why Choose a Cometic MLS Head Gasket for Your Honda B-Series?

Honda’s B-series VTEC engines are popular among enthusiasts because of their high-revving design, strong aftermarket support, and extensive engine-building potential.

However, reliable cylinder head sealing becomes increasingly important as combustion pressures and engine temperatures rise.

The Cometic C4231-030 features three stainless steel layers designed to accommodate the small amounts of movement that occur between the cylinder head and engine block during normal engine operation.

Its coated and embossed outer layers help distribute sealing pressure around the combustion chambers.

For properly prepared engines, this construction offers a durable alternative to conventional replacement gasket designs.

FYI: How to Diagnose a Blown B18 Head Gasket

Before replacing a head gasket, it’s important to identify the original failure.

Common symptoms include unexplained coolant loss, persistent white exhaust vapor after warm-up, cooling-system overpressurization, misfires, and oil/coolant contamination. No single symptom proves that the head gasket has failed.

Our How to Fix a B18 Blown Head Gasket guide covers the repair process on an Acura Integra, including cylinder head removal, component disassembly, and preparation for replacement. The example uses a non-VTEC B18B1, so B18C VTEC procedures and gasket selection will differ.

FYI: Is an 81mm Head Gasket Right for Your Honda B-Series?

Gasket bore and compressed thickness directly affect engine assembly.

An 81mm gasket opening must be compatible with the engine’s actual finished cylinder bore. On a rebuilt engine with oversized pistons, a larger gasket bore may be required.

The .030-inch compressed thickness also influences piston-to-head clearance and static compression ratio. A thinner gasket does not automatically improve engine performance, particularly if it reduces mechanical clearances beyond acceptable limits.

If you’re uncertain which B16 variant is installed, consult our How to Identify Your Honda B16 Engine guide before selecting replacement parts. It explains the differences between common B16 engine generations and how to identify them.

How to Install a Cometic MLS Head Gasket on a B-Series Engine

Correct installation is essential to maintaining a reliable seal.

1. Remove the cylinder head following the applicable Honda or Acura service procedure.

2. Inspect the cylinder head for warpage, cracks, and corrosion.

3. Check the engine block deck for flatness and surface damage.

4. Verify that both mating surfaces meet Cometic’s MLS surface-finish requirements.

5. Confirm the finished cylinder bore and gasket thickness.

6. Clean the sealing surfaces without gouging or scratching them.

7. Position the gasket using the correct alignment dowels.

8. Install the cylinder head and tighten the fasteners using the applicable torque procedure.

9. Reassemble the timing components and verify camshaft timing.

10. Refill the cooling system, bleed trapped air, and inspect for leaks.

For engine builders planning a VTEC cylinder head conversion, our How to Assemble Your LS/VTEC Build guide covers head studs, cylinder head preparation, and additional engine assembly considerations.

Important: The C4231-030 is not Cometic’s dedicated LS/VTEC hybrid head gasket. For a VTEC cylinder head installed on a non-VTEC B-series block, verify the appropriate hybrid-specific gasket, such as Cometic C4237-030.

Frequently Asked Questions

Does the Cometic C4231-030 fit a 1999–2000 Honda Civic Si?

Yes. It is listed for the 1999–2000 Honda Civic Si equipped with the B16A2 DOHC VTEC engine.

Will this gasket fit a 1994–2001 Acura Integra GS-R?

Yes. It is designed for the B18C1 engine used in these vehicles, provided the engine’s cylinder bore and other dimensions are compatible.

Does the C4231-030 fit an Integra Type R?

Yes. The B18C5 engine is included in Cometic’s listed applications.

Can I use this head gasket on a turbocharged B18C?

The MLS design can be used in properly engineered turbocharged applications. Boost pressure, engine tuning, head clamping, and sealing surface condition all influence reliability.

Is the Cometic C4231-030 a complete engine gasket kit?

No. This product contains one cylinder head gasket. Valve cover gaskets, intake manifold gaskets, head bolts, and other replacement components are sold separately unless specifically bundled by the retailer.

Does this fit a Honda B18B1 non-VTEC engine?

Not as a direct application. Cometic lists the C4238-030 for standard B18A1/B18B1 non-VTEC configurations with an 81mm gasket bore and .030-inch thickness.

Upgrade Your Honda B-Series with Cometic

The Cometic C4231-030 MLS Cylinder Head Gasket combines three-layer stainless steel construction, an 81mm bore, and .030-inch compressed thickness for compatible Honda and Acura DOHC VTEC engines.

From factory-style engine rebuilds to carefully planned performance projects, this gasket offers a precision-engineered sealing solution for properly prepared B-series engines.

Shop Honda engine rebuild components and performance replacement parts at Pro Street Online.