Originally Posted by crassius
those studs come in several diff threads - sometimes with interference threads at the top - be aware of this when you look for replacements or do re-tapping
This is a topic that needs to be out there more. Some, not all but a fair amount of engines come with cylinder/head studs that have fine and course threads. Usually the fine threads are on the case end and the course on top where the head nuts go. This has caused not a few problems for the inexperienced when they remove the studs then not noticing the different threads try to reinstall the studs and the result is usually stripped threads on both ends and lots of headaches for the builder.
If you remove a stud check it carefully for the thread pitch on each end. The difference in the threads is noticeable. As Crassius said, they are 8mm x 1 for the fine thread and 1.25 thread for the course. And to repeat AGAIN, don't use those chrome acorn nuts; but the do make good slingshot ammo.