EST

[Steve Knickerbocker 512-356-3000 X6759]

          Assuming a V8, reconfigure as necessary for your application.
          Why don't you use 5 imbedded magnets in the harmonic balancer and 
          two pick ups to determine firing positions.  Four of the magnets 
          would be 90 degrees from each other, starting at TDC for #1 
          cylinder.  Place these four magnets at the outter edge of the 
          balancer.  The fifth magnet would be positioned at TDC for #1 
          cylinder as well but at the inner edge of the balancer.  One pick 
          up would sense the four outer magnets and the second sensor would 
          sense the fifth magnet.   If you don't have room to run the pickups 
          side by side then off set the fifth magnet, x# of degrees from TDC 
          for #1 cylinder, and the corresponding pick up.  Just make sure 
          both sensors read both magnets at the same time. I'd dial in the 
          maximum ADVANCE you want and use the controller to delay from max 
          advance based on the knock sensor and to a lesser extent the 
          coolant temp sensor.  Remember too much advance can cause 
          overheating.  I'm pretty sure you would'nt even need a vacuum 
          input, for advance based on vacuum.  Just input the spark knock 
          signal and the pick up signal to a variable delay ckt, o/p that 
          signal to all divide by 4 (/4) ckts, o/p /4 to ignition coil driver 
          ckt #1 and to /4 ckt #2, etc. for however many coils your running.  
          The ignition coil driver ckt will need to determine dwell and 
          handle the current necessary to drive your choice of coils as well 
          as limit the current so you don't burn your coil out.  Just 
          thinking here.  I'm not an engineer just a tech but I think this 
          might work.  If any one wants to help me prototype a schematic and 
          help me out with component selection I'd be willing to cobble a 
          prototype ckt, at my expense and test it on my Dart.  I'd even post 
          the results and share the info with all of you.  Email me if you 
          like.  See acsii "art" for /4 ckt.
          
          Steve M Knickerbocker
          STEVE.KNICKERBOCKER at SEMATECH.ORG
          
          sensor 2 i/p   _____                                               
          --------------| /4  |-.-----------    to coil driver #1
          --------.-----|_____| |
          sensor  |   __________| trigger for next /4 ckt
          1 i/p   |  |   _____ 
                  |  '--| /4  |-------------    to coil driver #2
                  '-----|_____|
          obviously these need to be triggerable divide by four ckts.  The 
          trigger for #1 /4 ckt is the pulse from the second, fifth magnet, 
          pick up.  all others will be triggered by the preceeding /4 ckts 
          o/p to the coil drivers.  What say you?