Reinforced head gasket Lancia Delta Integrale HF 2.0 8V 16V 831B5 831C5 831D5 831E5

The Lancia engines covered

The 2.0-litre turbocharged Lancia Delta HF 4WD and Integrale, in 8-valve (831 B5, 831 C5) and 16-valve (831 D5, 831 E5) form, take the same reinforced Cometic cylinder head gaskets.

On the 831 B5 and 831 C5, the original gasket carries part number 5891307, or 5891308, 7540289, 7540290, 7604263, 7604264 and 7662197 depending on the version; on the 831 E5, 7540379, 7660966 or 7709257. Lancia publishes neither its construction nor its thickness; its bore is 85 mm. It is sized for standard combustion pressure: when that pressure rises, clamping load drops, the cylinder head lifts, and coolant passes into a cylinder.

Reinforced cylinder head gaskets

A cylinder head gasket does not create the seal on its own: it holds because the fasteners clamp the head against the block. A composite gasket is crushed for good beyond 100 N/mm² of admissible stress, whereas the 301 stainless steel of the MLS gaskets withstands 517 N/mm², 5 times more, and springs back at every combustion.

This page offers the part numbers from Cometic, a racing manufacturer, in MLS multi-layer steel construction. Gasket bores run from 85 to 86 mm, covering the standard block as well as the rebored block, and thicknesses from 0.69 to 3.56 mm, enough to adjust the compression ratio without touching the pistons or the cylinder 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

Gasket volume: the space the gasket leaves above each cylinder. It enlarges the combustion chamber, and the larger it is, the lower the compression ratio. Values compare with one another at identical gasket bore.

Preparation and fitting

Before fitting, check the flatness of the cylinder head and of the block with a straight edge and have them skimmed if necessary. These gaskets require no sealant: Cometic supplies them already coated.

Technical guide

The construction offered

Cometic MLS Several stamped and riveted stainless steel layers. The outer layers carry active beads around each cylinder and each fluid passage. Sealing is achieved with a moderate clamping load and limited bore distortion. This is the versatile choice, from a prepared naturally aspirated engine to light forced induction.

Choosing bore and thickness

Gasket bore. The Cometic MLS comes in 85 and 86 mm.

Thickness. Lancia does not publish 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.

With a thickness finer than that of the removed gasket, measure piston protrusion above the block with a dial gauge: it is what determines the remaining clearance between piston and cylinder head.

The brand

Cometic Gasket, Inc. is an American manufacturer of engine gaskets and sealing solutions, founded in 1989 and based in Concord, Ohio. Its speciality is the made-to-order gasket, in the bore and thickness required. All its products are made 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 85 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: 5891307, 5891308, 7540289, 7540290, 7604263, 7604264, 7662197 (831 B5, 831 C5) ; 7540379, 7660966, 7709257 (831 E5).

Important: the other 2.0-litre Fiat and Lancia engines (Fiat Coupé, Lancia Thema, Dedra, Kappa) are not covered by the Cometic part numbers on this page.

Why switch to a reinforced gasket?

A reinforced gasket holds where the standard one reaches its limit: at higher combustion pressure it keeps its shape instead of being crushed.

As soon as power goes up, turbo, supercharger or raised compression ratio, the head gasket becomes the weak link of the top end. Switching to a reinforced gasket is then not a comfort but a safeguard: it is what prevents the failure and the head removal that comes with it.