Dave,
You assertions about the vacuum module are correct. The vacuum module acts like a switch, giving 10° of retard at idle. The precise specs are: 2° retard at 3.3 - 4.3 inches of vacuum, and 8° retard at 3.9 - 4.9 inches of vacuum ... those are the only two test points given in the service manual.
All of the 2.7 CIS engines used the same distributor as the 2.4 'T' engine and all of the distributor curves are posted from spec book and service maual in the following thread:
http://www.pelicanparts.com/ultimate/Forum3/HTML/009677.html
According to both Haynes and BA ... the '77 49-state cars had timing set at TDC.
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Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler
[This message has been edited by Early_S_Man (edited 10-16-2001).]