Thanks Kermy. Will do. 
Rennie

100 hp is pretty good for a 1275, so my guess is it has a 'cam'. The motor should run below 2500 rpm but be 'rough'. I would be inclined to start a separate thread about the problem.

Good point/question.  Here are my specs:

1275cc (probably bored a bit, but don’t know)
#4 = 165psi
#3 = 170psi 
#2 = 170psi
#1 = 173psi
new Bosch Blue 3 ohm coil
new “Classic Mini Ultrik 8mm” spark plug ignition wire set
new NGK resistor type spark plugs
valves adjusted to spec for “Stage Two” head (had everything rebuilt by MiniMania mechanic many years ago, do not know how to tell which cam I have… Mechanic said “about 100 hp”…)
new 123Ignition Pre-A+ 123DIST-A distributor - advance curve set to “D” (I think)
static timing set by my Prius mechanic ( !!! )
Weber DCOE40, fresh foam air filter
no headers 
Mini Mania standard exhaust
temperature stays about 185 after warm up
oil pressure about 60#
about 5000 miles since rebuild

starts easily/immediately when cold. Difficult to start after warm up. 
ran adequately before new 123 distributor, daily driver
runs great after new distributor, once it reaches 2500 or so
engine dies from idle, changing Weber idle screw doesn’t help

What cam do you have? Missing/coughing below 2500rpm sounds like long duration race cam issue.

I don't know but presumably the 65D electronic has one curve, programmed to replicate what the new non-electronic does.
That would suggest the curve would be specific for a particular engine build/installation when new. As an engine ages its needs apparently change. Add to that the non-factory upgrades and owner tinkering.

Are they user re-programmable? If so How?

The 123, depending on the model, gives you either 16 preset curves or something that is user programmable.

Based on what I know (meager as it is) from the 123 info, at 5000rpm, your advance curve would top out there, whatever maximum advance is set. So theoretically, apples to apples, performance would be the same. At 2000 to 3000 rpm mid range driving, is where the curves vary most, though not by much. A particular engine, depending on its state of tune and build, might need more or less advance at any given rpm. The upshot is to find the curve that makes your engine run best at all speeds.

With the 123 I bought, the first 4 curves advance from 10 deg to 28 max. Within each curve, the mid-range advance varies from 14.5 deg to 20.2 deg. at 2000 rpm.

All curves idle at 10 degrees.

For the second set, the max is 30 deg, with the mid-range varying from 16.3 to 21.1 deg.
For the third set, max is 32 deg with mid-range from 16.2 to 22.9 deg
For the fourth set, max is 34 deg with mid-range from 17.0 to 23.9 deg.

One of the factors to review is what maximum advance at 5000 rpm is safe for your engine. Once you settle on a curve, it can be "tweaked" by changing the static timing from 0 at TDC. So, for example with the first group, if you wanted 29 deg at 5000 rpm you could advance the static by one degree, which would "shift" the entire curve. That's beyond me!

Confusing the result would be the effect of the vacuum advance depending on throttle position. (Too much info?!)

Another question to add to the mix, with a comparison of the factory 65D distributor.  Besides the adjustability of the 123, where is there a performance difference between the 65D electronic dist  and the 123? I can see the benefits over a mechanical points distributor. If I drive at the 5k rpm level am I going to notice anything? Would I notice anything between driven 2K & 3K rpms?

The set-up says to keep working your way thru the curves till you get pinging then back off to the last setting. The bluetooth is for changing the setting via bluetooth. Once set you should not have to change unless you change something on the motor.

My next question is, this 123 Distributor allows the owner to set the running of their via the 16 presets depending what they have in the engine.What is the USB And bluetooth for? Don't you set and forget or do you have to keep adjusting for the life of ownership?

Vacuum advance is generally a fuel economy feature. By advancing the spark at idle and low rpms it allows for a leaner fuel mixture for idle and slight throttle opening such as when cruising around town. As the engine revs up, the amount of vacuum seen at the distributor dissipates and the vacuum advance receded. Meanwhile, since the rpms are increasing the mechanical advance (or electronic programmed curve) takes over.

Apparently early Cooper S cars and racers don't need it as the engines are worked hard and seldom see part-throttle. They aren't worried about fuel economy

I had an early 123 dist that failed (water damage to the circuit board). The USA supplier wanted more for the replacement circuit board than I wanted to spend (over half the price of a complete replacement 123 dist assy at the time). So a points dist went back in.

About 3 yrs ago I picked up a CSI Ignition distributor with 16 advance curves and have been very happy with it. Advance curve selection is as simple as removing the dist cap and resetting with a small phillips screwdriver. Also the CSI dist looks like it came from Lucas. And I want to say the CSI product is a little easier on the wallet as well. 

If you are thinking about going down the adjustable electronic distributor path I recommend taking a look at what CSI Ignition offers as well. 

Thanks for the replies so far. I see there are several options. I get the split between an A and an A+ engine. What about the vacuum? With and without.

I've been running one for over 10 years. Hasn't missed a beat and the car starts every time. Ditto to what Dan said.

Kelley

The 123 Ignition system for Mini was developed by Marcel Chichak  https://www.starchak.ca/

Note his website has apparently not been updated since 2007. However there is a lot of stuff about Minis, among his other interests.
Unfortunately the link to the 123 section give me a warning... something about an expired time certificate. The destination for the link may have been hacked or some other Internet reason for it not working. Beyond me!

I bought a 123 ignition system a long time ago when I was advised the dizzy in my Mini's engine had worn bearings/bushings and produced erratic timing. As there was no identifying tag on it, I was suspicious about whether it actually belonged to the engine, or was "bodged in" ( the MG Metro type 1275 high compression engine came to me with intake and exhaust systems for a 998).

So, I bought an early version of the 123. Besides being shiny new and fresh (just like in the pictures) and the fact that Marcel had worked on developing the advance curves specifically for Mini, it has some really convenient features.

1. It was very well constructed and fit perfectly.
2. It had a small rotary switch inside the bottom (accessed through a hole) with 16 positions to select one of the 16 advance curves. More about that below. I believe newer models have the switch accessed by removing the dizzy cap - much easier or are programmable (you make your own curve).
3, It would operate on 4 volts to 15 volts, Negative earth in temperatures -30 C t500 and 1000 rpm o 85 C. (You wouldn't want to be driving a mini at -30... been there, done that).
4, It would operate on a stock or high energy coil, not below 1 ohm. (My car has a ballasted ignition system which works fine.
5. Available for A-series and A+ series Minis, with or without vacuum advance.


Advance curves were in four groups. All had 10 degrees advance between 500 and 1000 rpm. (Advance below 500 rpm is Zero, a nice idea on a engine reluctant to start). Maximum advance for the 4 groups in degrees at 5000 rpm is 28, 30, 32 and 34. The curves between range at 2000 rpm from 14.5 to 23.9, each curve being different.

Installation was a breeze. Besides the high tension leads, there are only two wires - red gets power from the switch side of the coil and a black wire goes to the other low tension coil terminal. First, you set the engine carefully to top-dead centre. Then you select an advance curve based on your engine's build. Then you install the 123, connect the red and black wires, remove the dizzy cap, then rotate the body until one of the LEDs inside lights up, with the rotor pointed to where the No.1 cylinder HT lead will be. The ignition needs to be on (engine not running) to power the electronics. Then clamp down the body and make an index mark (scratch etc.) so when you want to change curves you don't need to turn the engine to TDC. "Gentlemen... start your engines." THats pretty much it.

However, the suggested curve may not be right for your engine, Small upgrades like free flowing exhausts, improved induction etc, mean that your engine will likely want something different. I had to try 3 or 4 different curves to fine the one the engine is happiest with.

It is recommended that you change the cap and rotor every 30,000 km. I haven't touched mine since. For me it was worth every penny,

Because the item 123 Distributor was brought up in another thread, I realized that I know nothing about this part. Going on this site, I see that there are several models and are pricey. Those that have this part and are using it; please give me your take.