Does the advertised valve stem length include the Clik core?

No. The advertised Clik stem length is measured from the base to the top of the stem, excluding the Clik core.

The installed Clik core adds 13 mm. For example, a 40 mm stem measures 53 mm with the core installed.

When choosing a stem, also allow enough exposed valve above the rim for your pump head to connect. Total assembled length is not the same as exposed length above the rim. If you need help choosing, send your rim depth and pump-head model.