I visited the JAE website pointed to in the previous message. They specify
a primary circuit with at least 1.5 Ohms. This is probably due to the
limits of the switching device, as Myles pointed out. I would say either
rig a resistor bypass as described, or put some resistance back in. Some
Alfas have this arrangement, with a resistor that's shorted out while
starting.
On another note, the resistor does something else besides keeping the coil
from burning out. The actual waveform of the spark is partly determined by
the resistor. While it's true that less resistance puts more energy into
the coil when the points are closed (L/R relationship), it also makes the
energy produced dissipate faster (RC relationship). This means you get less
spark duration. I tried running my old Mallory coil without the resistor,
and sure enough, it burned out the points AND the center button on the cap.
It ran badly, too. All those second-order differential equations I hated
in college DO have an application. ;=)
MHKitchen@aol.com wrote:
>
> In a message dated 4/27/99 11:11:51 AM Pacific Daylight Time, brian@uunet.ca
> writes:
>
> << My
> theory on no resistor >>
>
> You're correct, no resistor means more voltage at the coil and more current.
> It also helps for starting. That's why many stock cars have a resistor
> by-pass circuit that's engaged during starting only. THe problem with
> leaving it out all the time is that it tends to overheat the coil at idle, or
> stall conditions, and can either prematurely burn out the points or
> overstress the switching transistor in the ignition module, if its not rated
> for that current level.
>
> Myles
|