32v I have no idea, but on the Euro 16v the piston cuts seem much deeper than clearance in normal operation would require. The valves are up in the heads from the deck and IIRC the lift is .474/.432 int/exh. If I get the chance its something I intend to measure.

I am buying a timing belt fail Euro S motor with valve damage, so that chance may come soon.

I've taken advantage of the fact that mine is not an interference engine to run it some while I troubleshoot other problems..but I have absolutely no history on this car, so the belt could be the original one. I think i've decided to let the mechanics have this first round, will let me focus on the other things that still need work..sunroof, gauges, etc etc.

When i take it to them I'll have them look at the rest of the drivetrain..I've always held out that if the basic repair things cost too much I would just get rid of the car (but working on it already I'll probably end up being one of those doofs that pays $10k in repairs on a car that's worth $7k)

How experienced is the shop you are using with 928's?

Most of the timing belt problems we hear about, except for pure neglect, are shops that made outright mistakes or just shoddy work. Do it yourselfers also make mistakes, but they tend to be detected immediately and corrected.

What motivates me to try it myself is the LOAD of while your in there work thats more time consuming than skilled.

There is nothing to screw up on a belt change on a 928 the hard part is removing the crap to get there. Then line up the timing marks pull the old belt off fit newbelt check timing marks (if you know where or what they are)roll over 2 revs recheck marks. Most important water pump and tensioner bearing if in doubt chuck it out. Belt tension is important but not rocket science I use belt deflection of about 4mm on longest run its easy to check regularly remove belt cover on rh side check tension .Try doing a 911 with a dti and clocking it in or even an aston martin dbs.

I think you've got it right jsbc, replace everything you have any doubts about. Most shops want the car in and OUT, not opened up taking a service bay with parts all over waiting for a new tensioner boot or water pump bolt to be shipped, so the old one goes back in, and the bomb starts ticking.

I may compare a few different ways of measuring tension including recording the tone of some segment of the belt when plucked like a guitar string. Once you have a reference its supposed to be very accurate.