Years ago, when I was making my first crank-trigger distributorless
ignition, I used a few turns of wire wrapped around the spark plug lead to
measure the spark output and timing advance of the system. The voltage
generated was on the order of hundreds. It doesn't take a long piece of
wire running near, and (geometrically) parallel to a spark plug wire, to
induce enough voltage to cause the MSD (or your tach, or whatever else) to
false trigger. Using non-suppression wire makes the situation way worse.
Theo Smit
tsmit@home.com
B382002705
On Friday, October 22, 1999 12:57 PM,
STUART_BRENNAN@HP-Andover-om3.om.hp.com
[SMTP:STUART_BRENNAN@HP-Andover-om3.om.hp.com] wrote:
> Another Theory: The text of the MSD warning as quoted a couple messages
back
> specifically says that operation of the MSD could be disturbed by RFI,
such as
> that produced by solid core wires. This indicates that whatever control
> circuitry is in the box can get confused, and maybe it won't be making
sparks
> quite the way it should. The interference wouldn't have to break anything
to do
> this. It would probably work fine away from the rpm range where the
sparks
> happen at just the right time to screw up whatever important decision the
> control box is making.
>
> Stu
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