Reinforced head gasket Ferrari F120A F40

The Ferrari engines covered

The F120A is a Ferrari V8 petrol engine. It powers the Ferrari F40, listed in the compatibility table below.

The original gasket carries part number 136795, which supersedes 147362. Ferrari gives neither its bore, nor its thickness, nor its construction. Each bank of cylinders takes its own cylinder head gasket, calculated for the original combustion pressure; beyond it the clamping force loses effect, the head lifts slightly and coolant can reach a cylinder.

Reinforced cylinder head gaskets

Sealing does not depend on the gasket alone, but also on the bolts that pull the head down onto the block. Past 100 N/mm², a composite gasket takes a permanent set; the 301 stainless steel of MLS gaskets withstands 517 N/mm², 5 times more, and springs back at every combustion. Likewise inspect the head bolts and replace any that are stretched or damaged, on both heads.

This page presents 1 part number from Cometic, the American maker of competition gaskets: the C4482-067, an MLS, multilayer steel, with an 84 mm bore and a 1.70 mm thickness. The engine takes two gaskets, one per bank of cylinders: order two units for both banks. Together with the chamber volume, its thickness sets the compression ratio reached 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. The part number is sold individually and for one bank of cylinders only: one is needed on the right and one on the left.

Technical specifications

A gasket's volume is the free space it leaves above each cylinder; it comes on top of the combustion chamber and lowers the compression ratio. Only compare gaskets of the same bore, 84 mm for this part number.

Preparation and fitting

Before refitting, check with a straightedge the flatness of the gasket faces of each head and of the block, and have those that need it machined. The Cometic gasket arrives already coated: add no sealing paste. Also clean the gasket faces of both heads carefully before fitting.

Technical guide

The construction offered

Cometic MLS Several layers of embossed stainless steel, held together by rivets. Each outer layer has active beads around every cylinder and every fluid passage. A moderate clamping load is enough to seal and the bore distorts little. This versatile gasket suits anything from a tuned naturally aspirated engine to light boost. The part number on this page comes in this construction. Here it serves both banks of cylinders of the Ferrari V8.

Choosing bore and thickness

Gasket bore. The Cometic MLS C4482-067 is offered in 84 mm.

Thickness. Ferrari does not state any thickness for the original gasket 136795. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

Before settling on any thickness other than the original, read with a dial gauge how far the pistons stand proud of the block's gasket face: it gives the clearance left between piston and head. This V8 has two banks of cylinders: take the reading on each.

The brand

Cometic Gasket, Inc. is an American company founded in 1989 and based in Concord, Ohio: it designs and builds gaskets and sealing elements for engines. Its reputation comes from custom gaskets, cut to the bore and thickness asked for, made in the United States from American materials. Its part number for this Ferrari is offered here in 84 mm.

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 84 mm bore of this 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: 136795.

Important: the part number on this page suits only the F120A engine: check your Ferrari's engine code before ordering.

Why switch to a reinforced gasket?

When the original gasket reaches its limit, the reinforced one takes over: under greater combustion pressure it keeps its shape instead of sagging. For the Ferrari on this page, it is the solution as soon as the engine exceeds its original output.

Higher compression ratio, more power or revs pushed hard: in every case the cylinder head gasket becomes the weak point of the top end. A reinforced gasket prevents the leak and the head removal that would follow, far more expensive than the gasket itself. On this Ferrari engine it is the first part to deal with once the original output is exceeded.