Thanks for the suggestion, Doug.
In the old days before spray bottles were available, the trick was to pour a trickle of water down the carb from a coke bottle (which was easier with a down-draft carb). The risk was inducing water too fast and chilling a valve or other component and causing damage. The preferred liquid was auto transmission fluid, which produced humungous clouds of whitish smoke. Can't do that these days!

I have never bothered with cleaning sprays.  Consider trying a pump spray bottle full of water. 

Bring then engine to temperature, then raise the RPM to about 2k with the idle screws.  Spray a heavy mist of water into the carbs as you listen to the exhaust note.  Slow your pumping as you hear the RPM drop off.  Keep that up for a couple of cups of water then let the engine idle for a few minutes to dry the exhaust.

Update:

I finally got the Mini out for a brief spin and had a few short blasts of a couple of miles each between exits on the 4-lane. Not enough to fully clear out the carbon, I expect. But I did hit 125 kph (close to 80 mph) with some throttle left to space. Acceleration and power are very good for an un-rebuilt 1275, though I have nothing to compare it to. Best part is I did the run with the driver's window open and could barely detect an occasional whiff of exhaust, my clothes didn't stink when I got out, and there were no noticeable fumes in the garage after I parked it. No knocking or after-run (dieseling) when shut off.

Spark plugs are NKG BP6ES and in good physical condition.
 - plug 1: sooty outer metal and hook. Inner porcelain thinly black but going to tan on one side, maybe 1/3 tan.
 - plug 2: ditto - maybe 1/4 tan
 - plug 3: ditto - clearing to 3/4 tan
 - plug 4: outer metal sooty, hook ** tan!**, inner porcelain light tan!!

It is running well, so I think I need to decarbon the cylinders before attempting any further tuning. I may get a can of that de-carboning spray (I've used it before) and monitor the plugs.


 

The new coil measured 4,000 ohms on my 1k ohm scale. I'm beginning to suspect that range on my meter.... will have to get it checked. Checking plugs and retuning hasn't happened yet - poor weather and other commitments. I'll report when I get back to it.

Glad you cars running a bit sweeter Dan. SE Michigan seems to have   the highest # of ground hogs around. Had one take up residence in an area of the garage that I could not access. I hated to hurt the thing, but it wouldn’t take leave for an answer, I was really surprised how well the mini worked. That name comes from their warning call to others of their kind as they are nearly blind, also called a wood chuck.

Did you measure the new coil's secondary resistance yet?

Interestingly, either Standard owns Intermotor or Intermotor owns Standard Motor Products.  You will probably never need another coil but should you need to go back to that same supplier, ask about any of the UC14 Standard coils.  They should be 6V and suitable for use with your 1-2-3 and the car's ballast wiring.  As I mentioned earlier, if you are still using the factory white/pink ballast resistor wire, you might want to replace it with a discrete ballast resistor instead.  (Check out the Standard RU** series resistors from your local supplier).

A year ago a lady at church told me her nephew was afraid she had run over a 'marmot' on the way to their house in Michigan.  I had to go home and look up 'marmot' and found it is a fancy name for a groundhog... also known as a 'whistle pig'.

Re Doug's "OUCH!". That was the list price for a "Standard" brand 803 coil for ballasted ignition from a large parts jobber which happens to be close to where I live. List price actually $74.77 CDN. The other day I was talking to a "young lad" counter guy, who needed and older guy's help finding what I wanted and he quoted that price. But today, I got another older guy who knew exactly what I was asking for, didn't even ask the "what vehicle" question, looked it up in an ancient (paper! remember those?) catalog with no cover, then tore into the warehouse and came back with the coil. He sold it to me at the cost price of $50.49, so with tax it came to $57.05. Ooooohhhh... DEAL!

This jobber supplies garages, shops etc,  so they are very unlikely to stock "budget" (i.e. cheaply made) parts.

I have no idea how old the old coil is, but the engine is a pre-unleaded Metro HA83AA high compression unit that has never been opened, except to adjust valves. The coil is mounted on the last head stud, which in my case is a special extended stud with a conical tip. It has a second nut above the head nut. When I went to remove the two bolts from the coil clamp band, the bracket on the head just bent. That suggests the coil may be original to the engine, which I suspect is somewhere around 1984. I had to remove the bracket from the head and take it to the bench for penetrating oil and patience. All back together now! And running!

Onetim: FYI it doesn't smell as much now! Before, I'd pull into the garage with the front and back overhead doors wide open, parallel park the Mini to the side, wait for the breeze to clear things out, but I'd still get complaints when my wife parked her vehicle in the garage hours later. It is an attached garage-and-a-half with a well sealed wall between it and the house.

What in the world is a "whistle pig"?

As for checking plugs, that may happen tomorrow. Typically they are black and the heat range is what was recommended by a pro Mini mechanic years ago. I did go for a sprint around the block. Today, the exhaust smells sweeter and a little rich at idle with the choke on a bit, as it should. Pulling away from the end of the driveway, I got more wheel-spin than I expected, so that was a positive moment. (I tend to keep acceleration just below wheel-slip.)
My next step is to go through re-tuning to see if the settings improve with a new coil.

Something smells here, oh that's right, Dan's car. How do your spark plugs look? Black, tan, wet, dry, are they all even, what heat range? How long does your car take to kill a whistle pig in a 2 car detached garage with the door closed? mine does it in under 15 minutes.

OUCH !  Is that the Intermotor coil price or are you looking at things like the Flamethrower or MSD coils? 

For a standard ignition I would run a Brazilian Bosch Blue.  The equivalent for ballast ignitions would be the Bosch Red.  Both were running about $50 U.S. on Amazon the last I checked.  They are robust, epoxy filled coils running around 20kV output.   (Shop around.  You want the Brazilian models... no other countries of origin).  

That said, there is nothing that says you need a name brand killer high-performance coil.  With the electronic ignition you can open up the plug gap wider which will benefit from a high voltage coil.  However, if you are not opening the gap... any regular output coil will work fine. 

Regardless, unless something has led you to believe your 20 year old coil has failed (weird running situations) or unless you have seen oil leaking out of the coil... leave well enough alone and run what you have.  The resistance of the secondary windings is unlikely to "change" over the years and continue to work normally.

Thanks for the digging, Doug. I had a hard time imagining 1:1000 winding ratio.
Coil price around here is around $75 CDN, so not such an easy purchase unless I'm confident the old coil is weak.
I have a 123 electronic ignition in place of the old dizzy, but the operation of the coil is the same. (It runs fine on a ballasted system.) The coil came with the car back in 2002, so I guess it doesn't owe me much.

I know that the new electronic dizzys I am buying come with special coil that is only 3 OHMS.. First thing I do when I get in mini or moke.. is throw away  the old dizzy and coil in the trash..  later.bc  ps.. price for this  3 OHM coil is $30 from sport cars parts ltd. in Tenn..

The winding ratio determines the coil's potential output voltage and the ratio is not based on the 12 to 14V available from the car's electrical system.  The winding ratio is based on the voltage spike generated when the magnetic field in the primary windings collapses when the points open.  Therefore, you will see the winding ratio quoted more commonly as about 100:1   (i.e. If the voltage spike when the points open is 300V, the induced voltage in the secondary windings will be 100 times that... 300V x 100 = 30kV).  The winding ratio does not say anything about the winding resistance since primary and secondary windings are made from different diameter wires.

Dan, doing some additional digging I found information confirming your statement that on ballast coils the secondary windings should measure somewhere between maybe 8k and 13k Ohms.  I cannot tell you anything about your Unipart coil.  If in doubt, I would replace it so you know what you are starting with.
EDIT:  However, if I were replacing one ballast coil with another, I would add a discrete, external, ceramic ballast resistor at the same time and bypass the factory's white/pink ballast resistor wire inside the wiring harness.  Those pink wires have a reputation for failing and melting the insulation on a lot of adjacent wires in the harness.

Mike, as mentioned earlier, any coil resistance measurements are made with the wires (low tension and high tension) removed from the coil.

Mike: the instructions I found were to measure the primary windings between the positive and negative low voltage terminals (1 ohm scale) and the secondary between the positive low voltage terminal and the centre high voltage terminal (1000 ohm scale). Readings on the primary should be in the 1-ohm to 3-ohm range depending on ballasted or non-ballasted and the secondary between 7,500 and 14,000 ohms.

I want to know if my secondary reading of 3,000 is bad or OK for the Unipart ballasted coil I have. Unfortunately, it no longer shows its part number.

on the subject:  How do you test a coil?

I"ve got the ohm meter.  Where do I put the leads for primary
and where for secondary?

I"m guessing maybe incorrectly that this is when it's not energized, engine off.

It is definitely a ballast-type coil. The secondary being 3000 ohms seems extremely low from what I've read. Yes, measurements were done with all the coil wires disconnected.
Doug:
Any coil needs to put out a high voltage say for discussion 12,000 ( it may be higher). So, for a 12V coil to produce that, the ratio of windings should be somewhere around 1:1000. For a 6V coil it would need to be 1:2000.
A ballasted coil is supposed to run on about 9 volts, so its ratio would be 1: 1333. That suggests either fewer primary or more secondary windings. If ballasted coil has lower primary resistance than a standard coil, that suggests it has fewer primary windings and the secondary for both types would have about the same. Therefore the secondary for both should have the same resistance.

A ballast coil (sometimes called a 6v coil) will have a primary resistance between 1 and 2 Ohms.  A "standard" 12V coil will have a resistance around 3 Ohms but some like the Bosch Blue and a few others run closer to 4 Ohms.  

In general, a ballast coil may have lower secondary resistance to match its lower primary resistance but that does not have to be true.  It's all about the ratio of primary and secondary coil wiring loops.

Remember when making these measurements you need to disconnect the wires from the coil so your readings are not influenced by other components.

Sounds like the correct resistance for a ballist ignition. The primary resistance would be around 6 ohms for non ballast. If you had that coil it would be extremely hot to the touch after a ride. My mini stinks and runs great as well, In my case it is the result of too short a center exit exhaust pipe, and I have the mixture on the rich side.

In another thread, somebody mentioned that he had a running rich problem that was solved by replacing the ignition coil.
This led me to test my coil to see if it was the source of my car stinky running. It should be noted that everything else has been tried, the engine has lots of power, starts easily, idles fine and has no hesitation. But it stinks!

Various web sources say the secondary resistance should be anywhere from 7.5K oms to 10K ohms.
The coil is a Unipart for ballasted ignition, which my car has.
I took my trusty multimeter and observed 1.7ohms for the primary and 3K ohms for the secondary.

What should it be for a ballasted coil?