Reinforced cylinder head gasket Ford JQDA JQDB JQGA

The Ford engines covered

The 1.6-litre Ford engines on this page power the Fiesta VI, Focus III, C-MAX II and Grand C-MAX, B-MAX, S-MAX, Galaxy II, Mondeo IV, Kuga II and the Tourneo and Transit Connect, from 2008 to 2022, in Ti, EcoBoost, Flexifuel and LPG versions, as shown in the table below.

The original gasket carries part number 1 685 734. Ford publishes neither its bore, nor its thickness, nor its construction. It is sized for standard combustion pressure: when that rises, the clamping load drops, the head moves away from the block and coolant reaches a cylinder.

Reinforced cylinder head gaskets

Sealing does not depend on the gasket alone: the fasteners that clamp the head to the block matter just as much. A composite gasket takes a permanent set above 100 N/mm², whereas the 301 stainless steel of MLS and MLX gaskets withstands 517 N/mm², 5 times more, and springs back with every combustion. With the O-Ring, the stainless ring seals the combustion chamber on its own, and the gasket body closes the water and oil passages.

This page brings together the part numbers of two racing manufacturers, Athena and Cometic, in three constructions: the stainless-ring O-Ring and the multilayer MLS from Athena, the chamber-stop MLX from Cometic. Gasket bores run from 80 to 82 mm and thicknesses from 0.711 to 1.6 mm, enough to tune the compression ratio without touching the pistons or the head. 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 volume of a gasket is the space it leaves free above each cylinder. This space adds to the combustion chamber: the larger it is, the lower the compression ratio. Compare these volumes only between gaskets of the same bore.

Preparation and fitting

Before fitting the gasket, check with a straightedge that the head and block are flat, and have them resurfaced if needed. No sealant is required: Athena and Cometic supply their gaskets already coated.

Technical guide

The three constructions offered

	O-Ring / Cut Ring Athena A steel core covered with asbestos-free aramid fibre, around which a stainless compression ring is crimped on each cylinder. This ring concentrates the clamping load on a narrow band, exactly where the seal is made, while a silicone bead protects the water and oil passages. It is the construction that best withstands high combustion pressures, the one used on the most heavily tuned engines.
	MLS Athena Two to five sheets of AISI 301 stainless steel, laser-cut, embossed and riveted. A folded sheet surrounds each cylinder and forms a Gas Stopper that transfers the clamping load towards the combustion chamber, while beads seal the water and oil passages. A coating covers the outer faces: one layer withstands heat and fills small imperfections in the block and head, a silicone layer keeps the gasket from sticking when it is removed. It is Athena's all-steel solution, from the tuned naturally aspirated engine to moderate boost. Its thin layers let the gasket follow small movements of the head under load and keep a constant clamping pressure over the whole sealing line, cylinder after cylinder, at every engine speed.
	MLX Cometic Embossed, riveted stainless steel sheets, including a folded centre sheet that forms a stopper around the combustion chamber, under a high-temperature coating. The clamping load rises at that point without deforming the bore any further. It is the strongest all-steel gasket, designed for high boost; it is offered here in 82 mm, in a single thickness.

Choosing bore and thickness

Gasket bore. The Athena O-Ring comes in 80 mm, the Athena MLS in 80 mm and the Cometic MLX in 82 mm.

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

Because the manufacturer does not publish the original thickness, use a dial gauge to measure how far the pistons stand proud of the block deck: it sets the clearance between piston and head, especially if you choose the thinnest gasket.

The two brands

	Athena S.p.A. is an Italian maker of gaskets and engine parts, with its headquarters and main plant in Alonte, in the Veneto. It has other sites in Spain, the United States, Brazil and India. Its multilayer gaskets are fitted as original equipment by car manufacturers, and its racing range is designed and built entirely in Italy.
	Cometic Gasket, Inc. is an American maker of gaskets and sealing solutions for engines, founded in 1989 in Concord, Ohio. Its speciality is the custom gasket, made to the bore and thickness required, built entirely in the United States from 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 bore of the gaskets offered (80 to 82 mm) 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: 1 685 734.

Important: the gaskets on this page are listed for the 1.6-litre Ford engines in the table (2008 to 2022). For any other vehicle, note the engine code before ordering.

Why switch to a reinforced gasket?

When the original gasket reaches its limit, the reinforced one takes over: under higher combustion pressure, it keeps its shape and does not crush.

As soon as a turbo, a supercharger or a higher compression ratio is added, the head gasket becomes the weak link of the top end. A reinforced gasket prevents the leak, and the head removal that follows, far more expensive than the part itself.