Jim,
To keep it shorter I clipped all of the original post.
When my dad designed and built his electronic ignition the idea was to get
better mileage. the theory was higher voltage (35KV vs. 25KV) would let you
use a wider plug gap (0.035 vs. 0.025) and result in a hotter spark that
would make combustion more complete. So you get more out of a given unit of
gas a side result would be lower emission of un-burned fuel. That sounds
great except, burn all the fuel, in a hotter environment and the other fun
oxides (CO, NO etc) go up. I guess we could add a catalytic converter to
get rid of that.
The electronic ignition really does not come into it's own until we look at
the current very low (by comparison) emission cars. With all of the
monitoring that goes on in a current engine the keeping emissions level
correct requires the ability to time the spark to a fine degree.
If you look at my other post on current flow, you'll see I blew pretty badly
the "way it works." The higher voltage during start (ballast resistor out)
gives you a hotter spark. During run the ballast resistor brings the
voltage down to what is needed to make the bang. I've always wondered if we
use a bit of diesel tech here . The hot engine makes the fuel ignite easier
(compressed hot air/gas mix) so a it doesn't take as much of a spark.
The condenser acts to absorb the back EMF (from the various collapsing
fields) and stretch out the spark duration a bit. The back EMF (voltage) is
what causes the arcing at the points, which in turn destroys them.
On what will the engine turn with points vs. electronic, my Honda MC ('69
750 Pre-K1) would turn 12000 on points (2 sets). But that's more related to
engine size, bore vs. stroke, and all that other good stuff rather than
ignition system components.
Steve
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