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techtalk:ih:engmech03 [2019/06/12 03:11] hippysmack [79-85 models] |
techtalk:ih:engmech03 [2019/12/09 16:30] hippysmack [Aftermarket Head Gaskets] |
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| 1969 Iron Heads ((photo by Monte03 of the XLFORUM http://xlforum.net/forums/showthread.php?t=166440&page=6)) | | | 1969 Iron Heads ((photo by Monte03 of the XLFORUM http://xlforum.net/forums/showthread.php?t=166440&page=6)) | | ||
+ | |||
+ | ===== Aftermarket Head Gaskets ===== | ||
+ | Cometic MLS head gasket torque: | ||
+ | There are six torque values in sequence: 9-14-22-35-42-42 (all in ft/lb) \\ | ||
+ | When using aftermarket gaskets, it's important to note that the torque values in the FSM are for OEM gaskets. ((Hippysmack of the XLFORUM http://xlforum.net/forums/showthread.php?p=5793537#post5793537)) \\ | ||
+ | The OEM gaskets offer a squeeze factor unavailable with steel gaskets. \\ | ||
+ | When using the MLS torque specs, you'll find they are not that different from the FSM. \\ | ||
+ | For instance, after you get to 9 ft/bs, it's about a quarter turn to 14, then about a quarter turn to 22 and so forth. \\ | ||
+ | But using the actual values instead of counting turns gets a more even pull on all sides and allows you to feel when something isn't right. \\ | ||
+ | |||
+ | To torque the heads, start with all four bolts loose and then snug them all by hand. Do one head at a time. \\ | ||
+ | Tighten in sequence 1-2-3-4 to 9 ft/lbs. Then do the entire sequence again to 14 ft/lbs and so on until you reach full torque. | ||
+ | Pay attention to how the bolts pull. They should not spring back when you let go after turning them. \\ | ||
+ | That would mean your bolts are stretching and would need to be replaced. \\ | ||
+ | That would also mean they loosened after you thought you had them to the right torque value. \\ | ||
+ | Do not use oil in the cap nuts (only a very light 'touch' on the bolt threads for smooth mesh of the mating threads. \\ | ||
+ | Using too much oil on the studs or cap nuts can hydrolock the nuts and you'll never get the proper torque. \\ | ||
+ | Hydrolock of the nuts stops the nut from turning on the stud threads and the only thing the stud can do when torqued from there is stretch (twist). \\ | ||
+ | |||
====== Valves ====== | ====== Valves ====== |