THE FOLLOWING INFORMATION IS FOR '76 to '79 USA CARS ONLY!
Vacuum Connections
There is confusion due to the existence of the two different throttle bodies. There was one type of throttle body used from '76 to '79 USA cars, and a different type used from '86 to '89 USA cars. THE CONNECTIONS ARE NOT THE SAME BETWEEN THE TWO. They do not even have the same number of ports.
I did some searching in the forum, and someone has in fact posted the correct hose routing diagram for ALL '76 to '79 USA cars. The only difference between the California cars and other USA cars is that California cars have EGR and the timing cut-off valve. First, study the picture in billjam's post in this thread:
http://forums.pelicanparts.com/showthread.php?t=437913&highlight=boost+retard
This is exactly the arrangement that Porsche_930 has on his car. He has no EGR so the ports that we have labeled C and D should be capped. Ports A and B go to the vacuum control valve and warm-up regulator, respectively. Port E goes to Port 1 on the distributor, after passing through the thermo switch (Porsche_930 says he does not have it).
If you have thrown away the timing cut-off valve (labeled as item 9 in the diagram), the most conservative thing to do is leave Port 2 open. This will produce the most retarded timing under full load. If you want to mess around a little, you can tee Port2 into PortE as Fredmeister has done. This gives you more timing under full load, but maybe too much!
I will cover the function of item 9, which I would advise everyone with these years of 930 to keep, in another post.