C2270 3.8 Locating Cylinder Head Stud problems ?

[PeterCrespin]

I took the answer to mean they switched supplier some time ago but after you bought your stud 18 months ago?

The waisting is a bit like the collet groove in a valve stem - it’s a weak point but not necessarily critical if the diameter is the same or larger than, say, the minor thread diameter. I never willingly use cut threads on head studs, only rolled threads.

[splosh]

10.08mm on the cut of the thread to 8.79 on the taper, that's seriously a weak point and to that point naturally that "C2270" Stud is now in the bin.
Yes, agree a rolled thread is better and preferred in a racing spec engine such as the Aston I just restored.

[PeterCrespin]

Agree Clive. Didn’t know the numbers.

You doubtless gave them but my sight is a bit blurry, due to meds given in ER where they are fishing a bit of alloy grit out of my eye. Shoulda worn goggles drilling under the D :-(