RE: tractors & torque wrenches - help for a newbie

[MicroPilot]

On the last head I did, the rebuild manual said to tighten the head bolts to 100 ft lbs, then loosen 1/2 turn and retorque to 90 ft lbs. I asked my mechanic about this and he said it was to stretch the bolts before apllying the final torque to them.

 

[hobbyfarm]

</font><font color="blue" class="small">( ...manual said to tighten the head bolts to 100 ft lbs, then loosen 1/2 turn and retorque to 90 ft lbs.)</font>

That's the why of having the angle gauge - 1/2 turn = 180 degrees. Sometimes it may not be critical, but sometimes it may.

 

[Indydirtfarmer]

Also in play here is some bolts may be siezed (rust?) and will take tremendous applied torque to set them in motion, however they aren't actually "torqued" to that point. That's yet another reason to loosen, then re-tighten.