Minimum insertion level for Serotta Ti quill stem?

[tv_vt]

A friend has loaned me his old Serotta ti quill stem to try out on a bike with a threaded headset. The stem does not appear to have a minimum insertion line, so I'm not sure how far I can extend it above the headset. Anyone have any info on how far these stems need to be inserted for safety?

The only marking on it are the length and serial number stamped into it. Could that be the "line"?

Thanks!

Thom

[Frank Draper]

Thom, Keep at least two inches of stem inside the head tube.