True - the ignition relay certaily requires a lot less current to keep it
operated and hence feed a full 12v to the coil, but I wouldn't expect this
to start happening just as the temperature started rising, unless the
alternator had developed a fault. There has been no mention of the
alternator being replaced recently.
PaulH.
http://freespace.virgin.net/paul.hunt1/
-----Original Message-----
From: Rich Peterson <kerry3@earthlink.net>
To: paul.hunt1@virgin.net <paul.hunt1@virgin.net>; MGS <mgs@autox.team.net>
Date: 10 June 1999 05:01
Subject: Re: 1977 MGB-Running on
>>>Sounds electrical, like the coil still has some voltage fed to it.
>The
>alternator, while it is still spinning, can potentially (!) feed some
>current to the coil with the ignition off. But with the relative
>resistances of the lamp and the coil this should only result in a very
>small
>voltage across the coil, insufficient to maintain a spark (otherwise
>they
>would *all* run on.<<snip>>
>
>I disagree. This problem is very common in '77s not because of a wiring
>fault but because of an alternator problem. The original alternator's
>voltage regulator protected against current feedback through the
>ignition light (and the ignition relay & coil), but once you change the
>alternator or regulator, you run the risk of introducing this problem
>unless the regulator is exactly the same as the original one which was
>installed. Since it is virtually impossible to order a regulator which
>meets the OEM spec. for the '77 MY alternator, it makes more sense to
>install the diode in the ignition light circuit. I modified mine 2
>years ago and have not had a problem since.
>
>Rich P.
>
>
|