My stud snapped at the same torque as you have described in your thread... after torquing the first 10 head nuts to 21 ft/lbs per recommendation, #11 snapped before hitting the torque "click".
So, I have to take out the engine again and replace all other studs too?
I bought a complete new set when one snapped, replaced the broken one only. All studs tightened to 21ftlbs first time. Now18ftlbs only after the failure when one stud was replaced together with new head gasket. 24 hours later all nuts retightened one by one by unscrewing each nut 1/4 turn followed by retorque to 18 again, from center going outwards as head should be done. I marked some nuts to verify, nuts moved appr 2mm on the outer radius.
It must be a fabrication failure. In my world studs like these are manufactured in batches where a number of samples are tested to verify when stretch and snapping. It cannot been done here.
- The stud that snapped for me felt soft much earlier than the snapping moment, maybe around 15-18. Same for you?
You torqued them all to 21 2:nd time too?
EDIT: IN your old thread the studs look a littbe bit strange.
Are they mounted upside down with the longer thread upwards? Should be into the case if I recall correctly. I have pics of my stud failure home, long way from where I'm now.