[Healeys] coilt induction ingition

Thu Dec 29 13:31:12 MST 2016

No. A Transil across ignition points will result in little or no spark
at the plugs. The coil primary voltage needs to rise up to somewhere
around 400V, depending on the coil, in order to drive the HT voltage
across the plug gap (firing voltage). If it is clamped at 20V by the
Transil then the plug firing voltage will be 20V * the turns ratio of
typically 100:1 so 2000V which won't do anything useful. A capacitor
is the perfect solution here as it protects the points for a few nano
seconds as they open, then allows the voltage to rise up and drive the
spark across the gap.

Modern electronic ignitions don't need the capacitor as transistors
can easily handle 400V.

Andy.

On 12/29/16, Oudesluys <coudesluijs at chello.nl> wrote:
> I presume a larger capacitor might influence the speed of the collapse
> of the magnetic field, reducing the voltage produced in the secondary coil.
> To prevent arcing as much as possible in the Lucas fuel pump I now
> install a "transil" across the points instead of the earlier used and
> less effective capacitor or diode. This could probably also be done on
> the distributor points. As I do not run points any more so I cannot try
> it out myself.
> A transil is very cheap, $1-$5 depending on where you get them. I got a
> larger quantity for less than $1 a piece on eBay. I use a bidirectional
> one in the fuel pump to make them positive and negative earth:
> /1.5KE24CA,/ CA indicating it is bidirectional.
> May be worth a try?
>
> Kees Oudesluijs
>
> //
> Op 28-12-2016 om 22:56 schreef Ed O'Neal:
>>
>> Gents,
>>
>> By way of recap:  When the points close current flows through the
>> primary (12 volt) side of the coil.  When they open the magnetic field
>> around the coil collapses across the secondary coil windings (high
>> voltage) driving a high voltage current across the plug gap and firing
>> the cylinder.  At the same time the magnetic field also across the
>> primary windings attempting to drive a current across the open points
>> and creating a relatively high voltage (perhaps 400 volts) which will
>> want to arc across the open points and wearing them out quickly.  To
>> mitigate this a condenser (capacitor) is places between the points
>> coil connection and ground which absorbs the “shock” of the current
>> being driven towards the open points and reducing the potential for
>> arcing across the points allowing them to last longer.
>>
>> Question:  Why would a larger condenser (capacitor) not reduce the
>> potential for arcing across the points even more?  What might be the
>> down side of such an attempt???
>>
>> Thanks for your expertise in advance.
>>
>> Ed
>>
>> *From:*Healeys [mailto:healeys-bounces at autox.team.net] *On Behalf Of
>> *Al Fuller
>> *Sent:* Wednesday, December 28, 2016 2:40 PM
>> *To:* 'Healeys, Forum'
>> *Subject:* Re: [Healeys] Mount a coil on an alternator.
>>
>> Josef:
>>
>> Petty broad brush you are painting some of us with there… [Quote:
>> “People who swap a generator for an alternator like to modify in any
>> way.”] Without further comment to your over-statement, I WILL say the
>> following:
>>
>> I drive my car on multi-day cross-country trips and see the value in
>> installing a modern alternator.  The generators on our cars were
>> installed 50 years ago, and designed way before that to provide a
>> fairly modest output [~20 amps, if memory serves].  The generator was
>> barely able to supply the car’s needs as supplied, and modern use
>> calls for additional and more power-hungry apliances in the car, such
>> as headlights that actually light up the road ahead…
>>
>> I now have an alternator that will power the car, headlghts, the CB
>> radio I consider a necessity when driving in a multi car caravan,
>> etc.  An added bonus is if it happens to fail, rebuild or repar are
>> readily available.  Note that none of this drives me necessiarily to
>> any other modifications.
>>
>> Al Fuller
>>
>> al at bighealey dot org
>>
>> '65 BJ-8
>>
>> '85 Rx-7
>>
>> *From:*Healeys [mailto:healeys-bounces at autox.team.net] *On Behalf Of
>> *josef-eckert at t-online.de <mailto:josef-eckert at t-online.de>
>> *Sent:* Friday, December 23, 2016 4:07 PM
>> *To:* Simon Lachlan <simon.lachlan at homecall.co.uk
>> <mailto:simon.lachlan at homecall.co.uk>>; Healeys, Forum
>> <Healeys at autox.team.net <mailto:Healeys at autox.team.net>>
>> *Subject:* Re: [Healeys] Mount a coil on an alternator.
>>
>> People who swap a generator for an alternator like to modify in any
>> way. Anybody who knows more about electrics know there is no need for
>> an alternator at all on Healeys. its only to adjust the rehulator to
>> work as it should.  But that´s to difficult for most I suspect.
>>
>> those selling these alternators are quite happy to sell them as people
>> like to modify and they also sell you one of these performance coils
>> and they need to be kept cool and best is to put the coil in the boot
>> to keep it cool. Haven´t seen that so far but can´t await to see it.
>>
>> Josef Eckert
>>
>> Konigswinter/Germany
>>
>> -----Original-Nachricht-----
>>
>> Betreff: [Healeys] Mount a coil on an alternator.
>>
>> Datum: 2016-12-23T21:57:44+0100
>>
>> Von: "Simon Lachlan" <simon.lachlan at homecall.co.uk
>> <mailto:simon.lachlan at homecall.co.uk>>
>>
>> An: "'Healey Group'" <healeys at autox.team.net
>> <mailto:healeys at autox.team.net>>
>>
>> I’ve had an alternator in my BT7 for a while now.
>>
>> So, when I was doing the job, I looked at pictures of other people’s
>> installations. Nobody’s coil was mounted on the alternator as coils
>> were/are mounted on the generators.
>>
>> I didn’t mount mine on the alternator either.
>>
>> Now, I’m wondering why everybody found ingenious places to put the
>> coils and nobody ingeniously adapted their brackets to fit onto their
>> alternator.
>>
>> Do alternators get too hot? Do they give off some kind of magic death
>> ray that fries coils or what??
>>
>> Any reasons not to do it??
>>
>> Thanks,
>>
>> Simon
>>
>> 
>>
>>
>>
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