I agree with this theory but if the time differential is microseconds can
this have a real effect on the timing of the firing?  Figure at 6000 rpm
[not for long] the engine is firing 100 times a second, so each cylinder is
firing 25 times a second and a 1/25th of a second is pretty long compared to
a microsecond.  Or maybe not.  Doing this on the fly.

Mike

On 2/20/03 11:11 AM, "Steve Delanty" <laurasdog@WEIRDSTUFFWEMAKE.COM> wrote:

> At 10:25 AM 2/20/2003, you wrote:
>>> If gap is too short, spark happens early; if too long, spark happens late.
>>
>> Sorry to be negative... but WHAT ABSOLUTE TWADDLE -
>> the spark plug gap does not affect the timing one jot - weak spark, splashy
>> spark, no spark, good spark, but as for when it comes, no.
>
>
> Clive, I disagree with the above.
> When the points open, the spark does not jump immediately.
> The magnetic field takes some time to collapse and the voltage
> across the secondary builds up over a brief time until it has
> enough voltage to jump the spark gap. The wider the gap, the higher
> the secondary voltage must rise and it takes a longer time to reach
> this voltage. It's easily observable on an oscilloscope.
> How long it takes the coil to reach a particular voltage is a function
> of the inductance of the coil.
>
> Find someone who's got an oscilloscope and play with an ignition coil
> and spark plug and you can watch the secondary rise time for yourself.
>
> At 3600 RPM one degree of crank rotation takes about 46 microseconds...
> Changes in spark gap can definately make small but easily measurable
> changes in timing.
>
> Just my .02
> Steve
>