Head gasket
(→Head gasket sealants) |
(→Head gasket re-torquing) |
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===Head gasket re-torquing=== | ===Head gasket re-torquing=== | ||
| − | + | Stock replacement head gaskets do not generally need re-torquing however, all racing engine head gaskets should be re-torqued regardless of the type of gasket being used. The purpose of re-torquing the cylinder head bolts is to restore the proper stretch to the head bolts after the first heat cycle. Physics dictates that the engine assembly will expand as the engine temperature increases, this expansion will increase the compressive load on the head gaskets causing a seating effect sometimes referred to as creep relaxation in composite head gaskets. The seating of the gaskets and threads results in a comensurate relaxation of the head bolts when the engine cools. Re-torquing the head bolts/studs restores the proper stretch to the fasteners which will insure proper cold sealing of the gaskets as well as proper combustion sealing under full load. One re-torque is all that is necessary, subsequent re-torqing can cause plastic deformation (stretch) of the head fasteners and damage to the head gaskets.<BR> | |
| − | + | The process for re-torquing is as follows:<BR> | |
| − | + | Start the engine & run with no load until operating temperature is reached.<BR> | |
| + | Shut down the engine & let cool completely (overnight).<BR> | ||
| + | Retracing the original torque pattern, one fastener at a time, loosen slightly to overcome the friction set of the bolt or nut, then re-torque to specified torque setting. | ||
===When replacing a blown head gasket=== | ===When replacing a blown head gasket=== | ||
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