[PeteKz]

dannobee, yes the Dilivar studs were a bad experiment. I had two broken lower studs on my SC engine (w 64Kmi) when I rebuilt it 30 years ago. No more Dilivar for me after that. Please distinguish that I do NOT advocate reusing Dilivar studs--pitch them directly in the trash bin. I only advocate reusing Porsche steel studs, the same on the top row and bottom row. As Henry corrected me (thank you), Porsche didn't use Dilivar on all the 78-on engines, 930's being an exception, and I should have said '78-'89. And, as I have cautioned several times, only reuse them if they do not have mechanical or corrosion damage. Other brands of studs I'm not sure about.

There's another reason I advocate reusing parts: Those parts have proved their durability in actual service. They have passed the "infant mortality" phase during which manufacturing defects will usually manifest. That doesn't apply to all parts, only those that do not get mechanical wear from their use. E.g., I do not advocate reusing worn synchro rings in the transmission, or oil pumps in the engine, or visibly worn rocker shafts/bushings, or some other parts, unless they measure within service specs. If those measurements are good, then reuse them.

P.S. I'm still looking for the measurement of a new timing chain, between 20 or more pins in the chain. I want to compare that to the 4 used chains I have in my parts collection to determine how much wear timing chains get in service. The four chains I have are the same length, even though they have different miles on them, so at this point, it doesn't look to me like they wear significantly. I've also noted that on my engine the cam timing didn't change measurably in 20,000 miles. If the chain and/or sprockets were wearing/"stretching", the cam timing should change. Maybe it takes a lot more miles for that wear to become noticeable.