I would be *very* suspicious if any car of mine ran fine one day, would not
start the next and needed all the parts you describe.
The white/black wire should have 12v on it when the points are open and 0v
(ground) when they are closed. At least by seeing 12v you know the ignition
is getting through the coil, maybe it is just not getting to the points.
The wire can fracture inside the insulation inside the distributor body
because the vacuum advance twists the plate and flexes the wire. Is this a
25D (spade terminal on body) or 45D (black wire goes through distributor
body), BTW? Connecting a ground to the white/black would cause the warning
light to dim slightly (the coil takes a lot of current) and cause the tach
to flick (it is voltage pulse operated). If the points *are* doing what
they are supposed to position the king lead near the block and try flicking
the points to make a spark (watch your fingers). If that's OK check you
have the right plug lead order 1 3 4 2 anti-clockwise.
Usually if the points, condenser and wires are assembled incorrectly the
result is a permanent ground on the white/black.
PaulH.
----- Original Message -----
From: William Killeffer <wtkilleffer@tn.freei.net>
To: <mgs@autox.team.net>
Sent: Monday, October 30, 2000 3:38 AM
Subject: ignition problem
> Hello listers,
> A little background: I was adjusting the idle speed and mixture on my 74 B
> when I finally got it right. I shut the motor off and returned the next
day,
> and the car would not start.
> Since then, I determined that the ignition was at fault, and replaced the
> coil, points, condensor, rotor and terminal lead with new parts. The cap
and
> wires were nearly new when I bought the car in June. I also replaced the
old
> ground wire with a new wire because the cloth on the old had split in
> several places. This installation seems secure. However, none of these new
> parts improved the situation.
> I then proceeded as though this was a wiring fault and enlisted a friend
to
> help with some tests. The battery is fully charged. We used a multimeter
to
> test the white/black wire that plugs into the distributor and it is
reading
> 12 volts. However, the points do not spark when the ignition is on and we
> used a screwdriver to open and close them.
> We even went and put all the old parts in just to make sure the new parts
> were not at fault. BTW, the new parts are Sorenson brand purchased at the
> local Advance Auto Parts. Still no spark at the points, and the
white/black
> wire connection seemed secure on its new terminal.
> Strangely, even though no spark was present, sometimes the ignition
warning
> light would dim slightly and the tach would jump in response to something
my
> friend would do under the hood.
> He and I plan to do more work tomorrow, though we're not sure how to
> proceed. Is this a problem that electronic ignition would cure? I have
> between 4 and 6 months to get this car roadworthy in time for my wedding.
> Thanks for the help,
>
> William Killeffer
> 1974 MGB that doesn't run, making its brake light problem a non-issue for
> now
>
>
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