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| Mr. Gasket’s Ultra Seal head gasket configuration is based upon a material called “Grafoil”. This is a unique, flexible, non-asbestos material that remains stable at extreme temperatures. According to Mr. Gasket, Grafoil's superior heat dissipation properties eliminate hot spots, the primary cause of blown head gaskets and compression leaks. The 5-layer composite construction sandwiches the Grafoil material between two steel plates for strength, and then a special formulated elastomer coating is applied to both sides to provide added sealing protection against minor surface imperfections, creating a tight, leak proof seal across the entire sealing surface, even around water ports. | |
Have Gaskets Evolved That Much Over The Years?
Absolutely. As time has passed, cylinder head gaskets have changed dramatically. Because of this, there is a tremendous amount of choice available when it comes to head gaskets. Head gaskets are constantly being updated, and in many cases, later model "high tech" gaskets can often be retrofitted to earlier engine designs. The truth is, no single gasket is correct for all applications. The following is a compilation of the basic (and more common) gaskets you're bound to run across in drag racing applications:
Embossed Steel Shim: The embossed steel shim gasket was an early design that was inexpensive and heavily used by Detroit manufacturers. The design required the use of supplementary sealers to work properly, but managed to retain torque settings. The dilemma with the steel shim gasket is the fact that coolant tends to corrode the steel. Eventually, the gasket will fail and lead to engine damage. In addition, this type of gasket does not conform well to irregularities in the block and/or head surfaces.
Soft Face/Perforated Core: This type of head gasket is another early design. It did not require the use of supplementary sealers and due to the soft (and thick) facing material; it could conform to surface irregularities. Unfortunately, this gasket type had a tendency to compress and relax while in use (especially after the engine went through a heat and cool cycle). Because of this, it mandated a retorque in order to maintain an adequate seal. While this wasn't a problem on some engines, it spelled major grief on others -- especially when headers covered the bottom row of head bolts.
No-Retorque Clinched Core: The clinched core gasket is a modern design that eliminates hot re-torques. It consists of a clinched steel core, covered with a high density, high temperature expanded graphite or aramid facing. In turn, this facing is covered with an anti-friction coating. Typically, the clinched steel core gasket is dense enough to maintain torque and strong enough to resist blowout. The facing materials are dense enough so that they can't relax significantly. As a result, no retorque is required, but the gaskets will compress enough so that they will conform to surface irregularities. The coatings are used to seal minor surface imperfections and to resist friction. These coatings may be Teflon or silicone-based -- depending upon the engine operating temperature range. The anti-friction properties of these coatings are very important -- especially when dealing with engines that feature dissimilar head and block materials (aluminum and steel). The different expansion rates of aluminum and steel create a shearing action that will eventually kill a head gasket. If the shearing action is counteracted with an anti-friction material, the life of the gasket is improved dramatically. Finally, the anti-friction coatings just make life easier --especially when the engine is disassembled. Why? Simple. You don't have to spend time cleaning the gaskets off the head or block deck surfaces.
Typically, there are two special sealing features available in state-of-the-art no-retorque head gaskets: Sealing beads such as Fel Pro's "Printoseal Elastomeric" design or in Mr. Gasket's "Ultra Seal" head gasket increase clamping forces around critical openings (oil or coolant passages). Wire ring combustion seals may also appear in gaskets -- especially those destined for high output and racing applications. These sealing rings may be encased in stainless steel armor for increased strength. Typically, these combustion rings can be manufactured from copper or pre-flattened steel. The pre-flattened steel models are used with aluminum components to prevent "brinelling" (indenting into the soft aluminum).
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No-Retorque Solid Core: These contemporary gaskets are much the same as the "clinched steel core" models. The difference, of course, is the makeup of the core, which in this case is solid steel. In addition, the secondary layer of the gasket will include an aramid-based fiber facing. The other construction features and properties of the no-retorque solid core gasket are similar to the no-retorque clinched steel gasket.