Morris Minor Owners Club

Hi,MMOC friends,which wires go where on the coil terminals ?. If previously connected incorrectly,whilst trying to get a non-starter,started(and still doesn't),could any damage have been caused to other components,or wiring ??.My Moggs a 1970 saloon.Thanks,Tom.

Makes no real difference which way round the wires go (some say you get a bigger spark if wired correctly but I've not proven this fact). Correct way depends on the earth polarity of your car, so the wire from the points should be on the earth side of the coil.... Some coils are marked +/- and some are more helpful in that they will have one terminal marked "CB" which stands for contact breaker, ie points.

Hello Tom,

no you won't have caused any damage and the car will run even if the coil polarity is incorrect. Older coils were marked CB and switch, these were for positive earth cars, with cb being connected to the distributor and switch to the live feed from the ignition switch (If the car's polarity has been changed to negative earth then simply swop the coil connections). Nowadays just a simple + or -, the correct connection is that the wire from the distributor is connected to which ever coil terminal is the same as the battery earth, i.e. negative earth then - is connected to the distributor.
The reason for having the correct polarity is that it gives a more powerful spark.

Alec

Hello PSL,

you beat me to it.

It is a fact that the spark is stronger if the central electrode is live, due to it being much hotter which helps the electron flow.
(Which is why electron valves had heaters, to stimulate the electron flow.)

Alec

Hi Alec
Yes, I can see the logic. It makes sense, thank you.

The greater spark is more to do with the internal wiring of the coil. But the difference is not great.

Hello Kitty fell,

it is the internal wiring that determines the HT polarity. The difference depends on the load, Minors do not require a particularly strong spark, engines with higher compression pressures and higher revs do.

Alec

Many thanks,everyone.My car is positive earth,so which coil terminal(mine has + and - markings) has the black and white wire to be attached to ?.
Regards,Tom.

If +ve earth then the dizzy wire (black/white) goes to the + terminal on the coil. It is the 'earth' route for the coil.

Thanks everyone for your very knowledgeable help.
Regards,Tom

With the coil connected to proper polarity the spark plugs will wear away on the ground electrode. If the coil polarity is backwards the plugs will wear away on the centre electrode. Takes a long time though.

I think that is caused by the battery polarity not the coil.

thanks forum friends can now fit new coil to my "56 tinworm farm" in compleat
Faith
Happy motoring

Could be genuine, this car was only at auction a couple of weeks ago.....

Moggasser56 wrote: ↑Tue Nov 19, 2024 9:29 am thanks forum friends can now fit new coil to my "56 tinworm farm" in compleat
Faith
Happy motoring

Hello & welcome Moggasser, can you please introduce yourself on a new post of your own.
Just post in General Discussion.
Due to recent experiences with AI Spam, some of us are more than a little suspicious of ancient topics being revived.

Thanks.