No boiling water yet!
If it works the way I think it is supposed to, I actually like the idea of it closing the vacuum to the vacuum advance at idle.
It gives me tuning options.
Also I THINK that it switches at some point from engine vacuum to timed port vacuum. That's really what the question initially was getting at.
Either way, I'm ok with it. I probably will need to do the hot water thing to determine at what temp it opens and if it is simgle stage or dual.
I like the idea that it is still installed in the original thermostat housing. It is appropriate for a '68.
Now if I can only find a yellow plastic overlay for the ignition coil, like the battery top idea, I'd be happier.
Unfortunately, although looking great, the Marti Autolite spark plug wires crapped out already. Too bad. They looked great in the AUTOLITE cap.
I haven't thought about the original spark plug wires in 45 years. I was innocent then. I never realized how FREAKIN' BAD the original wire engineering was back then?