Reinforced cylinder head gasket Ford 1.8 16V Zetec-E

The Ford engines covered

The 1.8 litre Ford petrol engines (Zetec) EYDB, EYDC, EYDD, EYDE, EYDF, EYDG, EYDI, EYDJ and EYDL are fitted to the Focus I (hatchback, saloon and Turnier estate) and the Australian Focus listed below.

This original gasket carries the part number 1 308 383. Its bore is 81.6 mm; Ford publishes neither its construction nor its thickness. It is designed for standard combustion pressure: when that pressure rises, the clamping load weakens, the cylinder head lifts and coolant seeps into a cylinder.

Reinforced cylinder head gaskets

It is not the gasket alone that closes the circuit: the fasteners, by compressing the cylinder head onto the block, contribute half of it. Above 100 N/mm² of admissible stress a composite gasket settles for good; the 301 stainless steel of MLS gaskets holds up to 517 N/mm², 5 times more, and returns to its shape after every combustion.

This page presents the part number from Cometic, an American maker of racing gaskets, for a single construction: the multi-layer steel MLS. The gasket has an 81.5 mm bore, against 81.6 mm for the original gasket, and a thickness of 3.05 mm. As a rule, the gasket bore chosen is at least 0.5 mm larger than the actual cylinder bore. Each part number is sold individually, one gasket per engine.

Technical specifications

The gasket volume is the empty space it keeps above each cylinder. That space adds to the combustion chamber, and so lowers the compression ratio. The comparison holds only at equal bore.

Preparation and fitting

Before fitting the gasket, run a straight edge over the cylinder head and block to check they are flat, and have them resurfaced if necessary. Cometic supplies it coated: no sealing paste should be added.

Technical guide

The construction offered

Cometic MLS Stainless steel plates, stamped, laid one over another and fixed together by rivets. The outer plates show active beads around each cylinder and each fluid passage. Moderate tightening is enough to seal and the bore moves little. It is the all-round gasket, from a prepared naturally aspirated engine to moderate forced induction.

Choosing bore and thickness

Gasket bore. The Cometic MLS is offered in 81.5 mm (H1760), in that bore only.

Thickness. Ford does not state the thickness of the original gasket. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

Since the original thickness is not published, measure with a dial gauge how far the pistons stand above the block, especially if the removed gasket is thicker than 3.05 mm: that value gives the clearance left between piston and head.

The brand

Cometic Gasket, Inc., an American maker of gaskets and sealing parts for engines, was born in 1989 in Concord, Ohio. Its reputation comes from the custom gasket, cut to the bore and thickness wanted. All manufacturing remains in the United States, with American 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 81.6 mm bore of the original gasket 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: 1 308 383.

Important: the part number on this page fits only the engines EYDB, EYDC, EYDD, EYDE, EYDF, EYDG, EYDI, EYDJ and EYDL: check your vehicle's engine code before placing an order.

Why switch to a reinforced gasket?

Once the original gasket is outmatched, the reinforced gasket keeps control: under higher combustion pressure it does not sag and stays true to its geometry.

Adding a turbo or a supercharger, or raising the compression ratio, subjects the head gasket to the heaviest stress in the top end. A reinforced gasket removes the risk of a leak, and of the cylinder head removal that goes with it.