[Roadsters] Eliza Now Va

John F Sandhoff sandhoff at csus.edu
Sat Feb 14 20:14:13 MST 2009


Speaking of ignition wiring, it was written:
> So the B/W wire goes from the ignition switch through the ballast and
> hooks up with the y/w and then goes into the + side of the coil. Why
> does it do that and what effect does it have. And what is the point?

Easier starting.
The 'run' position of the ignition switch provides voltage thru the
ballast resistor (B/W). The coil then 'sees' about 6 volts during normal
operation. More importantly, this also limits current thru the points
(without the ballast resistor you'll likely burn out the points).

The 'start' position of the ignition switch not only provides voltage
to the starter solenoid, it also provides voltage directly to the coil
(Y/W). This full voltage provides for a more powerful spark to help
ignite a cold fuel mix (and halps compensate for the battery voltage
dipping during the start cycle - the load of the starter will pull the
voltage down to 10 or fewer volts. That's why the lights dim when you're
cranking).

BTW, early Roadsters don't have this bypass circuit.

-- John
     John F Sandhoff sandhoff at csus.edu  Sacramento, CA


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