Ignition timing reference points

[Stephen Dubovsky]

>I was thinking of adding a 256 or 360 slot optical interrupter disk into
>my distributor to give double the that number of edges every rev 
...

  The only problem I see w/ this is dirt.  The guys in the motor industry
very rarely use optical encoders because you get a few specs of dust on the
encoder wheel and things go crazy.  They almost always prefer some sort of
magnetic/hall sensor type pickup or use a resolver (and then a resolver to
digital converter) if higher accuracy is required.  If your interested and
dont know what a resolver is, I can type up some sort of "short"
explanation;)  Both of these methods are relatively insensitive to dirt and
grime (unless its a ferrous material...)

  Hope this helps...
SMD