Well, Graham, I think you're right that I'm right!

After a hopefully-this-will-get-rid-of-the-headache morning nap (it'd be so nice if our children (7 months + 4 years) would sleep past 8am ), I went out and had a play... I stuck my head further into the boot than I ever had before, to make sure it was negative earth. When I saw the "+" was definitely going to the loom, not the chassis, I felt a little more confident. I removed a coil mount bolt so that I could loosen the coil ring, so I could rotate it, so I could get an 8mm spanner on it (sometimes things are complicated - whoever installed it could've just left it so you could get a spanner at both terminals! ), I switched the double connection over, connected the two non-dizzy wires to the positive (instead of the negative), and hooked up the two dizzy wires. Got in the car, cranked it, smelled smoke.

Then it dawned on me I'd swapped the dizzy wires over as well as the other two. Made up a couple of new adapter wires (double female blade for the black/negative wire, double male blade + 1 female blade for the red/positive wire - so I could splice in the three wires to the positive onto the one double male blade adapter - didn't think to go and buy a ring end to hook over the terminal, not that it would've made life much simpler), switched the wires over...

Cranked it. Nothing. No spark. But no smoke, either - first time ever! Given there's still part of the electronic ignition module that's still blue (even if the baseplate is a smoky grey), I figure that means it's now right. There's part which is still blue, meaning it's not burned as much as it could do, but it's still largely black and there's no spark, so I've killed it.

Or, is it that I've killed the coil..?

So, time to head to eBay and send another $52 to the MG guy... Not his fault, but that doesn't make a bloke any happier. Thanks for the offer Mick, but I'd rather burn my only own money and time than burn someone else's time as well. Not that I'm expecting to burn the next one!

It appears I was doomed from the start, given my car is negative earth (which I checked before I bought the kit), but the coil was still wired positive earth. And the instructions don't have a diagram with them. And, before yesterday, I was a total and complete noob at this! I have a little bit more of an idea now... Still a noob, but not as bad as I was 24 hours ago!

A coil WILL work with points if hooked up backwards, but I believe:
1. Output voltage is lower
2. Folklore says it damages the coil, it will never work quite as well again, even if swapped back.

Mick, comments please...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I've heard this as folklore as well...but have not thought much about it...

The coil is wound in a particular way. Instead of being wound as a traditional transformer with a primary winding and a secondary winding, it has only a single coil of wire. This arrangement is called an auto transformer.

Flipping the terminals on the primary could upset the output as the magnetic field collapses, but I'm not sure of the physics. It know it does not matter on a normal transformer as the transformer looks the same to the input current no matter which end you aproach it from.


In this picture, flip the primary and secondary labels, and make the new primary side (12volt side) a small fraction of the height it is now...and you will have a ignition coil of sorts.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I've thrown it to a professor no less....I'll paste his reply....

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Wow... We are learning a lot today! Thanks for your continued help.

MG Guy no longer has any on eBay... Any other sources..? Thinking about buying from SimonBBC - he has two kits - the standard one, and this supposedly newer one with better heat management, for not much more. The dearer one would still be around $60 landed (£19.99 + £7.99 postage). Or is there another recommended supplier..?

When I got my Morris 1100 it had the coil hooked up for positive earth but the battery and charging system was negative earth.
The car ran Ok with no problems and it still ran Ok after I changed the wires around.
I didn't notice any difference when I changed it around.

I don't have a kick arse voltmeter good for 20kV, otherwise I might stick it on and find out.....

I should pinch a oscilloscope from somewhere and put a HV probe on it...
Flipside is I could set my dwell period to 0.002% accuracy

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Apparently, the new red units are more robust although the transistor is still the same. My guess is that they might have improved the mounting internally to get more heat out through the backplate.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

So (considering reliability) how dear are these things really, when a genuine Pertronix LU-143 for a 45D dizzy is only US$80.40, from http://www.vintageperformance.com/retro ... /lucas.htm
Post extra, but it was cheap last time I got one.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Well, if you only have to use one kit, not two... I'm sure it's a bit cheaper. And the only significant improvement - from what I can see - for the Pertronix compared to this cheap little unit is that it came with a proper diagram, which shows how a negative earth coil's wiring should be, but is available to anyone online.

Even using two, though... My first one from the MG guy on eBay cost me $53 including postage, and the Red one from Simon BBC is $56.25 including postage (PayPal's exchange rate last night was A$1=£0.48). The Pertronix Ignitor is $80.40, that's A$111.67 plus postage, if you can catch A$1 at US$0.72. So... You could currently buy two kits (one blue, on red) for less than the Ignitor - or, if you include Postage on the Ignitor, you could buy two Red kits. Could they be that much lower in lifespan and quality (provided you don't wire them up incorrectly!) than the Pertronix..? I know there are other options, which give much more flexible control over the timing etc, and they're probably worth the money. But if you just want to avoid having to worry about the condition of the points...

I'd agree with this one. My van when I got it had the coil wired up backwards and ran, but ran quite badly. Correcting the wiring didn't help, but replacing the coil and wiring it correctly did.

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Simon

The adventures of an owner builder in the Tallarook Ranges

quote from the supplier...I also asked about if there is a kit available for the 29d dizzy, these have a larger rotor button diameter to reach the pickups on the larger caps. The buttons in these kits don't fit as the spark would have to jump a long distance to get to the lead pickups...so it waters down the reat of his reply with regards to the improved heat dissipation somewhat.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Looks like you can use the red module for a 29D... I believe this eBay seller is a respected Ausmini member. Maybe there are bigger rotor buttons available, and it's just a matter of which one goes in the kit..? And, if the baseplate's different, maybe there's been a kit using the older/cheaper/hotter blue module..? I don't know. Just know that it looks to be the same red module, and this is a kit for a 29D. From a respected and trusted seller and member.

I do know that the MG Guy's been very kind to me about the one I fried. I emailed him to let him know they can be used in (most) 43D4's (as I'd always planned to), let him know it all fitted, the levels were right, etc, but I admitted I couldn't be 100% certain as my coil was wired incorrectly, and he was very, very good about it. So extra positive feedback for him.

"Sparedirect" on Ebay have them for $45

Sparesdirect0 is the MG Guy I was referring to. And, I have to say, they're very kind and good to deal with. Highly recommended.

It lives! I've put in a new module, and it lives.

I find it interesting, in this thread about Plug Leads the advice given is that Cylinder 1 is at 1 o'clock. Well, on my 43D4, with the way it's been setup (and remember, it lives!), Cylinder 1 is at 7 o'clock. I'm pretty confident I've got the cap on the correct way - there's a little tag on the body, which slots into the cap, which, on my car, is at 7 o'clock. And the module - which sits where the points were - is at the bottom of the dissy, from 4 o'clock to 8 o'clock. Given I've not had a dissy cap off before, I don't know if this is normal - perhaps my whole dissy was put in 180º out, with the coil wired positive earth, and it still somehow worked... I don't care - at least it's working!

Mick - did you get a response from the professor you asked about having the coil installed the wrong way?

I've taken a photo of the de-smoked and blackened module, one day I'll get around to setting up a photobucket/imageshack account and will upload it... After I get around to downloading it from the camera.

So, lessons learned:
1. Make sure your car is negative earth. This is the obvious one - it's listed all over the kits, etc.
2. Make sure your COIL is negative earth - all the wires going to the coil when it's on points should go to the Positive Coil Terminal, and the Points wire should go to the Negative Coil Terminal. As per the diagrams on page 2 here. This is the less obvious one - it's not listed anywhere on the kits, and we've discovered it's quite possible to have your coil hooked up positive earth on a negative earth car and still have it work.

Now, to figure out whether the smoke that's now appearing from under the extractors (cylinder 4) as they heat up is just a bit of spilled oil from the change I did the day I blew the first electronic module, or something more sinister... Might buy some degreaser tomorrow - if I can find an open shop.