Porsche Repair: Timing, vacuum lines, vacuum line

Question
I recently purchased a '82 924 Turbo.  I replaced the head and it's purring like a kitten.  I took it in for an emissions test and it passed.  My question is how do I know if my timing is set correctly.  I have a hanes shop manual and it refers to disconnecting some vacuum lines in order to set the timing.  I know I set it to zero when I installed the head, but I've since moved the distributor and using a timing light I don't seem to see the timing mark move.  It seems to be steady at about 30 degrees.  I must admit that I've not disconnected any of the vacuum system.  I know it was unusual to find that the distributor had no advance mechanism.  A bit confusing to someone who has most of my experience with american concepts.  also, I've learned a great deal about the porsche from attending school for aircraft maintenance.  a lot of similiarity to aviation.

Answer
Hi Steve,

This will be a more general answer because you'll have to get all the timing specs from the car's underhood label.  The vacuum being discussed is the vacuum line running to the distributor's vacuum advance mechanism.  Usually we disconnect that and plug it with a golf tee.  

Remember, the "timing" numbers are very conservative and generally designed for best emissions with some performance.  If you err, and you don't mind erring on the "more performance" side, the setting can be more advanced typically than the "requirement".  Til' the next smog check.

Dave