Topic: Cylinder Head Stud Problems--Need Help

[Schizo]

Hello,

I'm rebuilding the top end on a '73 CB350F.
Everything was going well but I have now broken 2 of the studs while trying to torque to the recommended 14.5 foot pounds.   They twist and break in the middle.  It doesn't feel like I'm over doing the torque.  Is this a sure sign of an out of calibration torque wrench or are these studs known to weaken over time?
Btw, all the threads were well lubed.

Your help is appreciated!

[bryanj]

If youve lubed the threads you are overtorquing the studs, not had much to do with the 350 as it didnt come to uk but definately NOT a common problem with any other four

[newday777]

Did you put the 14.5 ft pounds all in one step?

[Bodi]

 A twisting break is odd. I don't know how that much torque is applied to the stud if the stud and nut threads are good. There's obviously some, but the nut should turn on the stud rather than just twisting it.
I do oil the nut and head, and go through three or more steps of increasing torque to get to final torque. Then wait 24 hours or so and retorque to spec. It's good to heat cycle the motor a few times then retorque again... but this is a pain and I rarely do it. At least on the smaller engines the rocker cover will come out in frame.

[Tim2005]

Have you got a photo of the studs? The 400f ones, which are the same I think, are extremely difficult to break.