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 > |
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