GM ignition module spex

[Darrell N.]

Gentlemen:

I am considering building a micro controlled ignition system to replace 
the stock HEI in my 81 Z28.  What I propose to do is swap the standard 
4 pin module for a 5 or 7 pin module, add a MAP, knock,  (and possibly 
other) sensors and a 68HC11 MCU to control ignition timing.

I know the 5 pin module uses the stock mechanical and vacuum 
advance, and simply adds a retard capability in conjunction with a 
knock sensor.  The 7 pin adds full control over the advance curve 
without mechanical or vacuum advance.  The 5 pin would be a good 
starting point, and as my software progresses I could go to the full 7 pin 
implementation.

What I need is detailed spex on the control signals for the module.  I 
need to know electrical signal specifications (voltages, drive capability, 
etc), a description of each signal and what it does,  and a general 
overview of exactly how the system processes the signals from the 
module.  If anyone can point me at relevant documentation or has 
experience with this type of conversion, please let me know.  A web 
search got me no detailed data on this subject.

darrell n
Calgary, Alberta, Canada
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