Ignition timing reference points

[Kalle Pihlajasaari]

Hi William and All,

> From:  William Boulton[SMTP:boultonw at OntheNet.com.au]
>
> Like to add 2cents to the debate.  The best way (IMHO) to achieve any
> degree of accuracy with timing prediction is to run as many reference
> points per revolution as possible. I've see the result of 1/rev on a twin
> and that was a disaster. Engines just do not maintain consistent angular
> velocity during a revolution. I developed a simulator some time ago to
> test theory on this and found that good results are obtained with at least
> 6 reference points per rev. I tried a number of basic equations and
> settled on a variation of the one Chaxel used. Just multiplied the result
> by some large fraction just less than 1. Still easy in integer assembler.
> The problem in predicting timing stems mostly from dA and not dV.

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 
of the dizzy (or the same resolution on the crank).  Is one degree
on the crank accurate enough for a totally digital one or two of
design for a mapped ignition.  Interrupter disks like this are
available alone and have usually got an index mark at another
radius.  I could then just replace the cam section with a nice
shaft without the centrifugal advance (will the rotor still point 
close enough to the correct cap electrode if the rotor is not
advanced at all and the timing is ?

Just a few thoughts.

Cheers
-- 
Kalle Pihlajasaari     kalle at data.co.za
Interface Products     Box 15775, Doornfontein, 2028, South Africa
+27 (11) 402-7750      Fax: +27 (11) 402-7751