340 head torque requirements

jawbone said

I would agree stretch is the most accurate but is it necessary to consider in this application event though Hughes Engines want to torque rocker shaft hardware to 30 vs. SM 15 ft.lbs. If the fastener does not stretch then it does not hold effectively?

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30 ft lb sounds like too much. That is the same as 3/8 bolts. You would be safer using the 210/215 inch pounds for factory 5/16 bolts. A certain amount of stretch is optimal, think of a bolt or stud as a very stiff spring that clamps two parts together.