Head gasket for Johnson Evinrude High-quality marine engine spare parts. Reference to Johnson / Evinrude : 0325273, 325273 Fits: 2 STROKE ENGINES ONLY 5 HP 1980 - 1983 1996 - 1998 6 HP 1984 - 2005 7.5 HP 1980 - 1983 8 HP 1980 - 2005 A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. Gaskets are normally made from a flat material, a sheet such as paper, rubber, silicone, metal, cork, felt, neoprene, nitrile rubber, fiberglass, polytetrafluoroethylene (otherwise known as PTFE or Teflon) or a plastic polymer (such as polychlorotrifluoroethylene). One of the more desirable properties of an effective gasket in industrial applications for compressed fiber gasket material is the ability to withstand high compressive loads. Most industrial gasket applications involve bolts exerting compression well into the 14 MPa (2000 psi) range or higher. Generally speaking, there are several truisms that allow for better gasket performance. One of the more tried and tested is: "The more compressive load exerted on the gasket, the longer it will last". There are several ways to measure a gasket materials ability to withstand compressive loading. The "hot compression test" is probably the most accepted of these tests. Most manufacturers of gasket materials will provide or publish the results of these tests.