Reinforced head gasket Triumph TR4 and TR4A 2.2 HE0H

The Triumph engines covered

The HE0H petrol engine (2.2 litres, 2 138 cc), a four-cylinder with pushrod-operated valves, powers the Triumph TR4 and TR4A listed below.

The manufacturer publishes neither the part number, nor the bore, nor the construction, nor the thickness of this engine's original gasket. It is sized for standard combustion pressure: when that pressure climbs, the head loses clamping force, lifts off the block and lets coolant into a cylinder.

Reinforced cylinder head gaskets

The gasket does not guarantee the seal on its own: the fasteners that clamp the head onto the block weigh just as much. CFM-20 combines a galvanized steel core with a soft asbestos-free compound that makes up for small irregularities in the gasket faces.

This page offers the part number from the American maker Cometic, a specialist in racing gaskets, in a single construction: CFM-20. Its bore is 88 mm and its thickness 1.09 mm. It is sold individually: one gasket per engine.

Technical specifications

A gasket's volume is the space it leaves free above each cylinder. That space adds to the combustion chamber and lowers the compression ratio; only gaskets of the same bore are comparable.

Preparation and fitting

Before fitting, run a straight edge over the head and the block to check their flatness, and have either one resurfaced if necessary. Cometic checks the flatness of each of its CFM-20 gaskets.

Technical guide

The construction offered

Choosing bore and thickness

Gasket bore. The Cometic CFM-20 gasket is offered in 88 mm (C4152-043), with no other bore.

Thickness. No thickness is published for the original gasket of this engine. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

As no original thickness is published, measure with a dial gauge how far the pistons protrude above the block's gasket face, particularly if the removed gasket is thinner than 1.09 mm: this shows the clearance left between piston and head.

The brand

Cometic Gasket, Inc. is an American manufacturer of gaskets and sealing solutions for engines, founded in 1989 in Concord, Ohio. Its reputation rests on the made-to-measure gasket, cut to the bore and thickness requested; all production takes place in the United States, from 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 88 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: not published by the manufacturer.

Important: the part number on this page suits the Triumph HE0H engine of 2.2 litres (TR4 and TR4A): check your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

When the original gasket reaches its limits, this CFM-20 gasket takes over: the steel core keeps its shape under combustion pressure, while the soft compound on both faces follows the small flaws of the head and block.

On an engine driven to its limit, the head gasket is the first part to fail, the weak point of the top end. A reinforced gasket prevents the leak, whereas the head removal that follows, a long and delicate job, costs much more than the gasket.