Bob Palmer wrote:
>
> I can also believe that some form of electronic points would
improve this capability over mechanical points, since the current that can
flow through mechanical points is limited from a practical standpoint by
arcing.
Bob,
In a standard coil and battery ignition the points simply complete the 12v
circuit to the primary side of the coil. The spark at the plug is initiated
when the points open, which causes the collapsing magnetic field in the coil
to induce a high voltage current in the secondary coil which eventually jumps
the plug gap. The problem with point type ignitions is that there is an arc
produced across the newly-opened points as well that tends to shorten the life
and timing accuracy of the points. (The purpose of the condensor in a standard
ignition is to reduce this arcing.) Many coil and battery ignitions only run
the full 12v through the points during starting and drop via a resistor to
some lesser voltage (usually around 8v) during normal running. The dwell or
period of time the primary coil is being charged through the closed point set
decreases with rpm, which is not the ideal situation.
Aftermarket ignitions can give alternative methods of triggering spark
production (i.e. optical triggers, hall effect triggers), alternative methods
of spark production less tied to the dwell time (i.e. capacitive discharge),
or both. What you want to use depends on what problems with the c&b ignition
you are trying to solve.
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