Actually, the voltage at the points never exceeds 6 - 12 vdc (ballasted or
unballasted coil). The high voltage that the spark plugs use is generated
by the collapse of the magnetic field described below and it goes directly
from the coil to the dizzy cap via the thick ignition wire from the center
of the coil to the center of the cap. It does jump the gap between the
rotor and the end of the ignition wire that goes to the spark plug, and
again at the gap of the plug.
The points energize the primary windings (heavy wire on the outside of the
internals) when closed or making contact. When they open, the magnetic
field in the primary windings collapses causing a large voltage increase in
the secondary windings which is an iron rod with a thin copper wire wrapped
around it thousands of times.
Therefore, static timing is attempting to set the points so they are
beginning to open at the proper moment when the piston is at the optimum
position for ignition as measured by crank-shaft angle. In other words,
when the timing mark is at the pointer, the points should just have opened
(test light off).
----- Original Message -----
From: "Randall" <tr3driver@ca.rr.com>
To: <triumphs@autox.team.net>
Sent: Wednesday, September 09, 2009 11:50 PM
Subject: Re: [TR] Static Timing
>> randall - correct me if i'm wrong - the closed points create
>> a ground, and
>> opening them allows the electrons to flow on through to the
>> spark plug.
>
> Er, well, I guess kinda maybe ...
>
> Way I see it, when the points are closed it allows current to flow through
> the primary of the coil, which builds up a magnetic field in the core of
> the
> coil. When the points open, the magnetic field collapses very rapidly,
> causing a high voltage to be generated in both the primary and secondary
> coils. The voltage across the (now open) points goes to several hundred
> volts; but because the secondary has roughly 100 times as many windings as
> the primary, it's voltage goes into the tens of thousands of volts
> (hopefully whatever it takes to jump the plug gap).
>
>> and that is why nothing works if you install the points
>> incorrectly - they
>> create a continous ground. btdt
>
> Me too!
>
> Randall
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