Morris Minor Owners Club

Help ! I thought the scew was slipping on the points & letting them close but further inspection has revealed the plastic insulator which contacts the dizzy shaft has melted at the contact allowing the points to close.
The engine is a 1275 A plus originally from an Ital which I have installed into a 56 series II, it runs & starts really well for about 30 seconds then the points gap closes, the coil is also getting really hot.
The coil fitted is the one which came with the engine which came out of a later Minor
I think it may be a ballast resistor issue which makes the coil from the later car incompatable , if not what could be causing my problem ?

No model of the Minor ever had a ballast resistor fitted.

Willie wrote:No model of the Minor ever had a ballast resistor fitted.

No Minor ever came with an Ital 1275 A+ as standard either, so that doesn't really help tell if it's a ballast resistor (or lack thereof) problem in this case!

The Ital will have had a ballast resistor, so if the PO of the engine and coil did indeed use an Ital coil they might have fitted a ballast resistor to the loom too.

Are there any labels on the coil to give a clue as to voltage? And as you're running without ballast what about just using the original Minor coil instead?

As far as I know the points for an unballasted Lucas dizzy are the same as for a ballasted, but I suppose a coil getting way too much power might be doing odd things (like breaking down and shorting internally maybe?). I'd chuck a known 12v coil on and some new points and see what happens...

Thanks for the info, I have the old coil that was fitted to the 948 engine & a new set of points so I will swap them in as soon as I have a spare 10 mins.
The coil which came with the 1275 has been painted by the previous owner to match the engine & I can't find a single identifying mark.
At least if I have to buy a new coil I now know which type to buy, out of interest I have read of plenty of coil problems on this web site, is there a coil which tends to be more reliable than others (Lucas sport for example).

You stated in your first post that the coil came from a later Minor so I pointed
out that no minor ever had a ballasted coil to prevent you going up the wrong
avenue. If you have an original Minor coil then do try it. If you have a test
meter you could also removed the black/white lead from the side of the dizzy
and insert the meter in series between the lead the dizzy side contact.
With the meter set on at least 10 amps see what the reading is when ignition
is turned on. The basic question is: did the fault appear after you had changed something and if so what did you change. If you finish up changing
points/coil/condenser etc then change one item at a time so that you know
what cures the problem.

Help ! I thought the scew was slipping on the points & letting them close but further inspection has revealed the plastic insulator which contacts the dizzy shaft has melted at the contact allowing the points to close.

Does this mean that the internals of the dizzy are heating up as well as the coil ?
Have you checked what model dizzy you have and made sure you have the right set of points and coil to suit.

"Very hot" is subjective, of course. All coils get hot, but you should be able to keep your hand on it after it has been running for a long while.

Assuming that the coil is getting too hot, that is an indication that you are using a ballasted coil where you should be using un-ballasted one. (You're basically pushing 12v plus through a coil designed for 6v), so it will overheat. The ballasted coil should only get the full 12v while you are starting, after that, the ballast resistor should be in series with the coil and it runs on 6v.

The overheating coil may also be breaking down internally and allowing a higher voltage through the condensor than normal, which may have lead to the condensor failing as well.

That would lead to arcing across the contact points, that would heat up the points, which may, in turn be causing the contact heel to melt.

But all that in 30 seconds? Doesn't sound likely unless you've got some serious meltdown going on across the points.

Are you sure the heel is melting, and not just wearing quickly? There were a lot of threads earlier this year about a poor quality batch of points with red heels that wore down very quickly, but that was over hundreds of miles, not a few seconds.

I'd suggest new points (with a brown heel if you can get them) and a new condensor, together with the correct non-ballasted coil. Make sure you apply a little smear of grease to the cam lobes in the distributor when you fit the new points, to help lubricate the heeel and prevent premature wear.

Hi guys,

Very useful info all round, I reckon you guys are spot on about the unballasted/ballasted coil, the current coil is getting seriously hot (you can't keep your hand on it), the 30 seconds is only running time.
I have done some messing with the ignition on & would expect an increase in temp if the points were closed, however normally when running I would expect the coil to cool slightly from burning hot to being able to hold it.
The points are definitely melting & not wearing & there is a lot of arcing between the points when cranking & seeing whats going on.
Funny thing, when I first installed the engine I checked the spark was ok prior to adding fuel to the mix & thought wow! when I saw how big the spark was, now I know why !
I'll let you know how I get on.

New unballasted coil & points has sorted it.

Merry Christmas & thanks for the advise.

Doug.

Hi Rustaddict.
I have just been down this same trail, and found other's suggestions most helpful.
I had the same problem after fitting another distributor and coil to my 1952 Minor.
(Points closing after each 100 yards of travel)
"Must be the dizzy" I thought, but after ringing around, and further inspection, I found my new coil was not compatable, as it was a resistor type coil. Generating too much heat, and melting the plastic "cam rider?"
Fitted new points, and the original 1952 coil, Everything is hunky dory.
Message from all of that; If youare fitting a new coil to an older vehicle, look for one that does not require a resistor.
Barry.

This was many years ago.......and we all know now that 'It's NEVER the coil' - so indeed, stick with a good old reliable coil - some of the coils sold these days are not best quality - and yes, many are designed for ballast resistor use and only have ~ 2 ohm resistance. The coil for a Minor should be 3.2 ohms resistance. Welcome to the forum by the way!

your best sticking with a standard coil that works ,none of this fancy stuff