[T3] Ignition on with points closed.

[Don Robertson]

Alrighty then...  lets get more specific.  The problem occurs when 
(as it true of ANY electrical connection) the points are not 
completely closed, but when they are sitting more of less closed, but 
loosely.  If they are completely open, or completely closed with a 
good connection, there will probably be no problem.  As with any 
electrical connection, looseness causes arcing and heat.  For 
instance faulty electrical connections in an old house have caused fires.

In a 6 or 12 volt system there is not enough current to cause a fire, 
but there is enough to cause a pit to appear on one half of the 
points surface and a cavity on the other.  "Burned" was a poor choice 
of term.  If the points actually look burned, i.e. ruined with 
evidenced of black soot, the condenser is likely at fault.



At 08:16 PM 29/03/2016, you wrote:
>Don, please explain how the points will get burned even if they are closed
>while the ignition is on and the engine is not turning.  Virtually all the
>energy would be dissipated in the 4 Ohm primary coil winding, and while I've
>never measured the resistance of a set of points, I can't believe it could
>be more than a tiny fraction of the coil resistance, maybe 0.1 or 0.2 Ohms,
>so don't see how there could be a significant amount of heat dissipated in
>the points, let alone enough to burn them.
>I've never experienced burnt points even though the ignition would have
>occasionally been on for some time, eg when adjusting headlight aim, and
>I've never bothered to ensure the points are open.  Certainly the coil would
>warm up, as it dissipates about 40W with the engine static, and about 20W
>when running (figures from Motor Industry Research Association report on
>1969 FI Auto Fastback), so unless your hands are cold, there's no advantage
>in it!
>
>Obviously there's no gain leaving the ignition on unnecessarily, but I can't
>see how it would be a problem for the points, which are essentially just
>switch contacts.  Please explain if I'm showing my ignorance, but it sounds
>like something told to apprentices to emphasise the need to turn off the
>ignition and avoid flat batteries.
>
>
>Dave
>UK VW Type 3&4 Club
>===================

Don Robertson - (905) 566-0000
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