As a former electrical engineer (before I saw the light and started writing
software!) I've found the recent thread on Lucas coils and the need for a
ballast resistor interesting, however, in Mark Jurras' posting of 23/1/95
(1/23/95 for the colonials :) ) he agrees with Jerry that the ignition dwell
time is the same at all RPM. It is the dwell _angle_ that is constant with
the contacts opening and closing controlled by the eccentricity of the
distibutor spindle. The dwell time therefore varies in relation to the
RPM - the higher the speed, the less time there is to charge the coil.
Incidentally, on electronic ignition systems that I have worked on for Rover,
they aim to achieve a constant dwell time which (if my failing memory serves me
right) is around 3-4ms. At 6000RPM this equates to a dwell angle of around 140
degrees. The target coil current has been chosen as 6Amps which can be readily
achieved under most operating conditions.
On the matter of spooling and tipoz: everybidy mokes mistokes with there toping
and grammmer, wy shuld wee mak such an ishue ov it?
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Andy Ashworth
Software Consultant
Lloyd's Register email: tcsaca@uk.co.lreg.aie
29, Wellesley Road Phone: +44 (0)181 681 4723
Croydon Fax: +44 (0)181 681 4839
CR0 2AJ
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