I've just redone the ignition system on my vintage 58 Sprite. Put on a Mallory
dual-point distributor and a Mallory coil as well. A note found in the coil box
stated that OEM resistors should not be removed or bypassed when the Mallory
coil is installed. It went on to say that even if the vehicle doesn't have an
OEM resistor by design, one should be installed. That's Mallory's 2 cents...
probably generic advice for performance street cars.
A point made earlier about the ballast resistor being necessary to drop the
normal (alternator) voltage level of 15V or so down closer to the 12V
requirement of the ignition system sounded right to me. If you're running a 12V
system (no alternator) and throw a ballast resistor into the mix, your ignition
system may only be running at a fraction of design output. A professor in a DC
course told me that a 12V ignition system will refuse to function when the coil
voltage reaches 9.2V. To me, 9.2 V is not that far away if you're dropping
(losing) voltage through a ballast resistor in a battery-powered system that's
continuously being discharged.
BTW, for anyone depending on a Group 24C battery in their racer: a fully charged
battery - per the industry standards for 24C's - will last approximately 80
minutes with no other current draw other than the ignition system. Of course an
engine start-up or two, or a couple periods of sustained idling on the grid
reduces that 80 minutes substantially.
That's why I wonder how much margin for error there really is. If you have your
original 12V being reduced by the voltage drop (through the ballast resistor)
and that reduced voltage level is constantly decaying to a degree (no
alternator), and your ignition goes silent at 9.2 V, and maybe your voltmeter on
the instrument panel is 'a tad bit' off... I don't know - I'm going home and
pull-off that resistor!
G. Schulz in WI
58 Sprite (vintage)
82 Vette (street)
MHKitchen@aol.com on 04/28/99 12:14:24 PM
Please respond to MHKitchen@aol.com
To: simon@mondes.com
cc: brian@uunet.ca, vintage-race@autox.team.net (bcc: Gregory
Schulz/MED/IT/ATLAS COPCO)
Subject: Re: Sprite question/Ignitions
In a message dated 4/28/99 10:11:40 AM Pacific Daylight Time,
simon@mondes.com writes:
<< All those second-order differential equations I hated
in college DO have an application. ;=)
>>
Ouch....my brain hurts!!!
Myles
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