Can you spot what is missing (round II)?

[Pb3]

I was on my way to Oulton Park when something let go. I ended up doing 105 miles on track in a Citroen Xsara, diesel

[738 driver]

Does the snapped stud have any relationship with the broken cam lobe (in sequence)?

[Pb3]

That is an interesting point, and I can't answer. When I reworked the heads I reused the studs but did not put them back in the same locations, although the polylock bits where kept with the rockers. At the mo I believe the most likely cause is over tightening, as I know I tend to tighten both the hex bit along with the allen key grub screw. I have been doing that for the last five years and probably with too much force, to be on the safe side ho, ho, so perhaps have been lucky to date.

[738 driver]

Might be worth replacing them all Phil, looking at your photo the two cyls toward the rear seem to have considerably more stud-top showing than the cylinder at the front. It could just be the GM block's factory machining of the cam/crank bores or that you have had some of the valve seats/tips reworked. The ones I have done do have slight differences when the tappets are set but are pretty close to having a uniform appearance.
Maybe several are a bit stretched due previous tightening.

Good Luck.

[k wright]

This is prevented by a stud girdle, an easy addition to the motor.

[bluesatin]

And I have a lovely secondhand stud girdle for sale!!!!!!!