<VV> Coil voltage etc.

[Hugo Miller]

That's the first time I heard that it had anything to do with points, 
and I'm not convinced by it now. That's what capacitors are for, isn't 
it? The fact of the matter is that when you engage the starter, you will 
suck so much voltage out of the battery that there is only about 9v 
left, which compromises the spark if you have a coil that wants 12v. The 
solution was to fit a 9v coil and feed it 9 volts via a resistor, while 
giving it the full 12 volts, or what was left of it, when the starter 
was engaged.
Back home in the UK we never used this system, until Fords introduced 
it. And the British Fords were TERRIBLE at starting. I'm going back to 
the 70's. You would keep cranking for ages before you could persuade 
them to start, and sometimes you just gave up. And the clutches were 
impossible to bleed. And, unlike British cars, you couldn't take the 
sump (oil pan) off without taking the engine out. I have always hated 
Fords, and still do.
British cars of that era managed to start just fine with a normal 12v 
coil. But for taxation purposes, British cars always had smaller engines 
so took less power to crank over. (They used to be taxed on notional 
horse-power, which was effectively a product of piston area, so british 
cars tebded towards small long-stroke engines - which was why the Model 
T never sold in England). Some British cars with larger engines, like my 
XKE, run a 9v coil with a ballast resistor, but I never saw a system 
where the resistor was incorporated in the coil wire till I bought a 
Corvair.
Bottom line is, in the UK at any rate, 12v coils are labelled 12v, and 
9v coils are labelled 9v. That avoids any confusion.

On 2020-02-16 22:26, Seth Emerson wrote:
> When cars shifted from 6-Volt systems to 12-volt systems, GM and 
> other
> manufacturers labeled their coils for use on 12 Volt systems. At that
> time, they also decided that the current load on the points at 12
> volts with a full 12 volt supply, would degrade the points in a short
> period of time. In order to assure easier starting, GM juggled the
> circuitry to provide a full 12 volts while cranking to start, with a
> full 12 volts input, the coil could put out more voltage to supply a
> hotter spark while cranking. Once the engine started, dropping back 
> to
> around 9 volts provided running power and prolonged the point life.
> The whole "point" of adding the resistor into the circuit, via either
> a resister wire, or the white ceramic block with the mounted 
> resistor,
> was to prolong point life. Coils designed for this usage are usually
> labeled "For use with external resistor" Some companies - once they
> moved away from points - redesigned their coils to operate on a full
> 12 Volt feed. This works, as long as the electrical circuitry is also
> designed with a 12 Volt load in mind.
>
> The TSP distributor, the one than I helped bring to market is
> designed the way it is to make it easy to install. The internal
> circuitry is designed to operate on 12 Volts. The easiest place to
> provide that is at the coil, because the distributor is already wired
> to provide the coil with a points-open signal wire. There is no
> reason, however, that the wiring could not be split and provide a 
> full
> 12 Volts to the distributor and a resistance feed to the coil. I 
> built
> a couple of harnesses to try just that. It should work just fine, it
> is slightly more complex.
>
> If you want to know more about this possibility, let me know.
>
> Seth Emerson
>
> -----Original Message-----
>  From: Hugo Miller via VirtualVairs <virtualvairs at corvair.org>
>  To: virtualvairs <virtualvairs at corvair.org>
>  Sent: Sun, Feb 16, 2020 6:08 pm
>  Subject: Re: <VV> Coils
>
> So they're 9 volt then? They will be EITHER 12 volt, OR 'to be used
> with a ballast resistor'. They can't be both! If the resistor isn't
> working or has been bypassed, a 9 volt coil will (obviously) get hot.
>
> On 2020-02-16 20:13, Smitty via VirtualVairs wrote:
>> Yes Hugo. 12 volt coils. Marked on the side, to be used with
>> ballast resistor.
>> Sent from my iPad
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