Patton Dickson wrote:
>
> I ran by the local auto counter today to grab tune up stuff so I can work
> in the ignition over the next couple of nights. I updated to the push in
> distributor cap and modern silicon wires, but I forgot I would need to
> change the coil when I did this as my coil is the screw in type.
>
> The coil they recommend was a 12 volt internal ballast resistor coil, is
> this right for a 67 MGB converted to negative ground? I know the car
> doesn't have an external ballast resistor, but I can't remember if I need a
> ballast resistor at all.
The purpose of the ballast-resistor system is to help dodgy ignition
systems on dodgy motors still manage to work. The best setup, in my
opinion, is to have a top-notch motor and ignition system so it's
not needed.
The ballast resistor, along with a 9 volt coil and the switching to
put the resistor in and out of the circuit, are to make up for the
loss in electrical energy that takes place when the starter is being
actuated.
When cranking, the power available is a nominal 9 volts, so the
ballasted system connects the coil to full available voltage when
cranking and then puts the resistor in the circuit when not
cranking, so it still sees roughly 9 volts.
If you use a 12 volt coil with a ballasted system, it won't get full
power either cranking or not and so it may be dodgy.
If you use a coil for a ballasted system on a non-ballasted system,
it may get too hot from the overvoltage and may eventually fail.
I recommend the Lucas Sports Coil and a non-ballasted system as the
best bet for well-maintained LBCs.
-Rock http://www.rocky-frisco.com
--
Red Dirt Rangers (Rocky on piano): http://www.reddirtrangers.com
JJ Cale Live (w/Rocky): http://www.rocky-frisco.com/calelive.htm
The Luggage Fan Club: http://groups.yahoo.com/group/luggage-fans
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