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3.5L V8 - Rover V8
Manufacturers
3.5L V8 - Rover V8
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Reinforced Cometic head gasket, in multi-layer MLS. Sold individually, two gaskets per V8 engine.
The petrol V8 of 3.5 litres, engine codes 15G, 22D, 24D and 25D, powers the first-generation Range Rover and many Land Rover models (Discovery, Defender, 90, 110, 127, Perentie), listed below.
Two original head gasket part numbers are on record: AJM340 for the 15G, 24D and 25D engines, and ERR 7218 for the 22D. The manufacturer publishes neither their bore, nor their thickness, nor their construction. They are calibrated for the original combustion pressure: when it rises, the clamping load relaxes, the cylinder head lifts and coolant reaches a cylinder.
Sealing does not depend on the gasket alone: the fasteners that clamp the cylinder head onto the block provide a large share of it. A composite gasket crushes for good above 100 N/mm² of stress, whereas the 301 stainless steel of MLS gaskets withstands 517 N/mm², 5 times more, and recovers its shape after every combustion.
This page offers the part numbers from the American maker Cometic, a specialist in competition gaskets, in a single construction: MLS. The bore is 89 mm and the thicknesses run from 0.69 to 3.56 mm, which lets you adjust the compression ratio without touching the pistons or the cylinder head. Each part number is sold individually; a V8 needs two, one per cylinder bank.
| Gasket bore | Thickness | Gasket volume | Gasket type OEM not specified | Brand | Part number OEM AJM340 | ERR 7218 |
| 89 mm | 0.69 mm | 4.29 | MLS | Cometic | C4367-027 |
| 89 mm | 0.76 mm | 4.73 | MLS | Cometic | C4367-030 |
| 89 mm | 0.91 mm | 5.66 | MLS | Cometic | C4367-036 |
| 89 mm | 1.02 mm | 6.35 | MLS | Cometic | C4367-040 |
| 89 mm | 1.14 mm | 7.09 | MLS | Cometic | C4367-045 |
| 89 mm | 1.30 mm | 8.09 | MLS | Cometic | C4367-051 |
| 89 mm | 1.42 mm | 8.83 | MLS | Cometic | C4367-056 |
| 89 mm | 1.52 mm | 9.46 | MLS | Cometic | C4367-060 |
| 89 mm | 1.68 mm | 10.45 | MLS | Cometic | C4367-066 |
| 89 mm | 1.78 mm | 11.07 | MLS | Cometic | C4367-070 |
| 89 mm | 1.91 mm | 11.88 | MLS | Cometic | C4367-075 |
| 89 mm | 2.03 mm | 12.63 | MLS | Cometic | C4367-080 |
| 89 mm | 2.13 mm | 13.25 | MLS | Cometic | C4367-084 |
| 89 mm | 2.18 mm | 13.56 | MLS | Cometic | C4367-086 |
| 89 mm | 2.34 mm | 14.56 | MLS | Cometic | C4367-092 |
| 89 mm | 2.49 mm | 15.49 | MLS | Cometic | C4367-098 |
| 89 mm | 3.05 mm | 18.97 | MLS | Cometic | C4367-120 |
| 89 mm | 3.56 mm | 22.15 | MLS | Cometic | C4367-140 |
A gasket's volume is the space it leaves open above each cylinder. It adds to the combustion chamber and lowers the compression ratio; only gaskets of the same bore are comparable.
| Fasteners | Engines | Tightening torque |
| Original cylinder head bolts | 15G, 22D, 24D, 25D | not published by the manufacturer |
Before fitting, check the flatness of the cylinder head and block with a straight edge, then have them resurfaced if needed. Cometic supplies its gaskets already coated: no sealing paste is required.
 | Cometic MLS A stack of embossed stainless steel sheets, riveted together. The outer sheets carry active beads around each cylinder and each fluid passage. Sealing is achieved with a moderate clamping load and little bore distortion. A versatile choice, from the tuned naturally aspirated engine to light forced induction. |
Gasket bore. The Cometic MLS is offered in 89 mm, with no other bore.
Thickness. For the original gaskets, Rover publishes no thickness. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.
| Your goal | Thickness to choose |
| Keep the original compression ratio | Original thickness not published by the manufacturer: measure the removed gasket and pick the closest value offered, from 0.69 to 3.56 mm |
| Skimmed cylinder head, make up the lost height | The thickness of the removed gasket, plus the metal taken off when resurfacing |
| Forced induction build, lower the ratio | A thickness greater than that of the removed gasket |
| Naturally aspirated build, raise the ratio | A thickness smaller than that of the removed gasket |
As the original thickness is not published, use a dial gauge to measure how far the pistons stand above the block face before choosing a thickness thinner than the removed gasket: this reading gives the clearance left between piston and cylinder head.
 | Founded in 1989 in Concord, Ohio, Cometic Gasket, Inc. is an American maker of gaskets and sealing parts for engines. Its reputation rests on the custom gasket, produced to the bore and thickness requested, from American raw materials. |
| Criterion | Original gaskets AJM340 and ERR 7218 | Reinforced gaskets |
| Construction | Construction not specified by the manufacturer | Multilayer stainless steel (MLS) |
| Gasket bore | not published by the manufacturer | 89 mm |
| Thicknesses available | thickness not published by the manufacturer | 0.69 to 3.56 mm, 18 values |
| Compression ratio adjustment | None | Through the thickness chosen |
| Resistance to overpressure | Limited to standard output | Designed for forced induction |
| Model | Engine code | Power | Years |
| Range Rover I 3.5 Vogue 4x4 | 24D, 25D | 163 hp | 1985-1990 |
| Discovery I (LJ) 3.5 4x4 (SALLJG) | 22D | 154 hp | 1989-1994 |
| Discovery I (LJ) 3.5 4x4 | 22D | 166 hp | 1989-1994 |
| Discovery I (LJ) 3.5 4x4 | 15G | 133 hp | 1989-1990 |
| 110/127 (LDH) 3.5 4x4 | 15G | 116, 133 and 136 hp | 1983-1990 |
| 90 I (LDV) 3.5 4x4 | 15G | 116 hp | 1984-1990 |
| Defender Station Wagon (L316, L315) 3.5 4x4 | 15G | 136 hp | 1990-1994 |
| 88/109 MK III fermé 3.5 4x4 | 15G | 92 hp | 1980-1983 |
| 88/109 MK III carrosserie ouverte 3.5 4x4 | 15G | 92 hp | 1980-1983 |
| Perentie fermé 3.5 HD 6x6 V8 | 24D | 136 hp | 1989-1998 |
| Perentie carrosserie ouverte 3.5 HD 6x6 V8 | 24D | 136 hp | 1989-1998 |
| Perentie pick-up 3.5 HD 6x6 V8 | 24D | 136 hp | 1989-1998 |
| Land Rover Defender Pick Up (L316) 3.5 4x4 | 15G | 136 hp | 1994-2002 |
OEM part number: AJM340 for the 15G, 24D and 25D, ERR 7218 for the 22D.
Important: the part numbers on this page suit the engines 15G, 22D, 24D and 25D: check your vehicle's engine code before ordering.
Where the original gasket reaches its limit, the reinforced gasket takes over: under higher combustion pressure it does not crush and keeps its shape.
Once a turbo or supercharger is added, or the compression ratio raised, the head gasket becomes the weak point of the top end. A reinforced gasket prevents the leak, and the cylinder head removal that follows costs far more than the gasket itself.
