Ignition timing reference points

[Chris Morriss]

In message <2.2.16.19961008113303.0c5f7c70 at mail.vt.edu>, Stephen
Dubovsky <dubovsky at vt.edu> writes
>
>>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
>

I have often wondered about using a resolver on the distributor drive to
measure the position.  Although the new price is frightening, there is a
lot of old equipment around with them in at give-away prices.  At least
near me in Nottingham with its big military surplus dealer. (Anchor
Surplus).

My worry is whether they would tolerate going round at half crank speed
for hours and hours.  I know they have top quality bearings but is the
life adequate?  Its not too much problem digitising the sine and cosine
output signals.
-- 
Chris Morriss