Reinforced head gasket Rover MG Lotus Caterham 1.8 18K4F 18K4K 18K4G

The Rover engines covered

The 1.8 litre K-Series petrol engines 18K4F, 18K4K and 18K4G, four-cylinder sixteen-valve units, power the Rover, MG, Lotus, Caterham, Land Rover and other models listed below.

Two original part numbers exist: LVB500190 and LVB 000 320. Rover publishes neither their bore, nor their thickness, nor their construction. They are sized for the original combustion pressure: when it rises, the clamping load relaxes, the cylinder head lifts and coolant seeps into a cylinder.

Reinforced cylinder head gaskets

The gasket does not seal alone: the fasteners that clamp the cylinder head onto the block provide half of the result. Above 100 N/mm² of stress a composite gasket settles for good; the 301 stainless steel of MLS gaskets withstands up to 517 N/mm², 5 times more, and returns to shape after every combustion.

This page covers the part number of the American maker Cometic, a specialist in competition gaskets, in a single construction: MLS. Its bore is 82 mm and its thickness 0.91 mm. The gasket is always slightly wider than the cylinder: by convention, at least 0.5 mm more on the bore. It is sold individually: one gasket per engine.

Technical specifications

A gasket's volume is the space it keeps open above each cylinder. That space adds to the combustion chamber and lowers the compression ratio; only gaskets of the same bore can be compared.

Preparation and fitting

Before fitting, check with a straight edge that the cylinder head and block are flat, and have them resurfaced if needed. Cometic supplies this gasket coated: do not add any sealing paste.

Technical guide

The construction offered

Cometic MLS Stainless steel sheets, embossed, stacked and held together by rivets. The outer sheets carry active beads around each cylinder and each fluid passage. A moderate tightening torque is enough to seal and the bore deforms little. It is the versatile choice, from a tuned naturally aspirated engine to moderate forced induction.

Choosing bore and thickness

Gasket bore. The Cometic MLS is offered in 82 mm (H3043036S), with no other bore.

Thickness. Rover gives no thickness for the original gaskets. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

As the original thickness is not published, use a dial gauge to measure how far the pistons stand above the block face, notably if the removed gasket is thinner than 0.91 mm: this reading gives the clearance left between piston and cylinder head.

The brand

Cometic Gasket, Inc. makes gaskets and sealing parts for engines in the United States; the company was founded in 1989 in Concord, Ohio. It made its name with the custom gasket, cut to the bore and thickness required, using American raw materials.

Advantages over the original gasket

When a reinforced gasket becomes necessary

• Adding forced induction, or raising boost on an already turbocharged engine
• Cylinder rebored beyond what the 82 mm bore of the gasket offered covers
• Looking for a compression ratio different from standard, higher or lower
• Engine that has already lost its gasket, or is consuming coolant
• Competition use, where the gasket goes through repeated temperature rises

Vehicle compatibility

OEM part number: LVB500190 and LVB 000 320.

Important: the part number on this page suits the engines 18K4F, 18K4K and 18K4G: check your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

When the original gasket is outmatched, the reinforced gasket takes over: even under higher combustion pressure it does not settle and stays true to its shape.

With a turbo, a supercharger or a raised compression ratio, the head gasket is the first link in the top end to give way. A reinforced gasket rules out the leak and the cylinder head removal that follows, a job far dearer than the gasket itself.