Timing marks 911t? Help

[Tweedle]

HI,
why when I trying to tune my 911t (1969), the car will not running static timing at Z1, but will run at the plus 30 degrees mark.

Runs well, using the timing light (900rpm) set at the 30 degrees mark! Will advance beyond the mark when rev increased!

Have installed a new Bosch distributor with a MSD, have I installed incorrectly?

[Charles Freeborn]

Sounds like you may be a tooth off with your distributor install.

[Tweedle]

What do I need to do to fix it?
I set the engine Z1, lined-up the distributor with its mark - pushed down?
Am I clockwise too far or anticlockwise too far (by a tooth?)