Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - rod bolt stretch (poll)
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Old 05-26-2005, 09:17 AM
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Originally Posted by NDNslicks4me
It seems to be pretty unanimous. I wonder why the manufactures recommendations are so far away from the real world examples? Could the Tq # be a "theoretical" measurement(ie no friction)?

What many people do not realize about fasteners is how they actually stay tight.... They are really a spring in a sense. The stretch of the bolt it what keeps the nuts on. The stretch keeps the pressure on the nut, keeping it from backing off...not the rotational torque. I am sure there is a relations ship between the two that is exact in controlled conditions...... But engine building is seldom a controlled condidtion....L.O.L.

I am sure the torque is a acceptable way with good results but being a engineer i am a little more anal about things.... I never had a rod bolt failure when i did torque them and didn't check the stretch, but now that i have seen what happens i cannot bring myself to go back......

I have seen a few engines built with the nuts laying in the pan, both from proffesional and non professional engine builders, and i am sure that the reason was because the bolt was not stretched correct causing the nuts to come off and well you know the rest..........

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