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evieceli 07-19-2017 12:00 PM

123 Ignition confusion...
I have a 71 spider that I am currently restoring. I sent out my SPICA injection pump to Wes Ingram and it has since been restored. I spoke to him asking about a distributor and he suggested that I purchase a 123 ignition distributor. Here's where my confusion starts... I went on the 123 ignition website and found a few distributors that would fit my Alfa, yet other than general information such as with or without vacuum, USB, Bluetooth options, etc. There seems to be no information about what kind of cap and rotor it uses when one would have to replace it. I also would like to know if I could use solid core wires with it. Specifically, the OEM 7mm green wires for 105.62 , 1750 engines. I know that MSD warns not to use it in some of their distributors as I had run into that with my Corvette project... I'm not looking to custom tune this car, but do like the idea of a simple switchable setting (16 I believe) for advance curve and an LED that lights up when the distributor is turned to set initial static timing as to allow the car to fire up and run.

Any comments would be greatly appreciated.

Thanks :thumbup:

Alfajay 07-19-2017 12:32 PM


Originally Posted by evieceli (Post 7731714)
I'm not looking to custom tune this car, but do like the idea of a simple switchable setting (16 I believe) for advance curve...

There was an interesting post on this topic recently on the Yahoo discussion board for 750/101 owners. Send me a private message with your email address, and I'll forward it to you. The author of the post, Tom Sahines, is one of the AROC tech advisers and a very knowledgeable guy.

To make a long story short, Tom prefers the programmable versions of the 123 over the earlier models with the 16 fixed curves.

GTVMk1 07-22-2017 12:08 AM

Hi Evieceli,

I just installed one of these this week, and they are very easy to do.
The Installation Manual includes info on what Bosch caps & rotors are used, so easy to replace.
I chose the cheaper option with the 16 predetermined advance curves, which I believe is all you need unless you are building a bespoke racing engine or you want to continuously fiddle with the settings.
I have a mildly tuned 1750, but was advised to run it on Curve #1 which is the standard 2L setting. Car is running fine, but I will also have it tuned on a dyno to ensure I have the optimum advance setting.


GTVMk1 07-22-2017 12:10 AM


Hi Evieceli,

Above is the link to the 123 site. You can ask them about the compatibility of your HT leads.

gprocket 07-22-2017 05:52 AM

1882 Attachment(s)
I think the 123 tunable (Bluetooth) is really handy if you are inclined to mess around with your advance curve. If you are just looking to stay stock and your current dizzy is in decent condition I would save yourself a couple hundred bucks and get the Pertronix ignition module. Takes about 10 minutes to swap it for the points and condenser.

alfaparticle 07-22-2017 05:57 AM

I have had my 123 distributor for 10 years and I have posted lots of information, much of it here:

I would go with the original, less expensive version. The canned curves are good for any naturally aspirated motor.
Solid core wires are fine. I have used no other kind with the 123.
The rotor and cap sold by the US importer are of good quality but based upon my experience it will be a long time before you need them.

I recently saw the dyno sheet for a 2L motor that made 230 HP at 7000 rpm. It has a 123 distributor set to "D" curve. I agree with the poster who suggested curve #1 for your car.

evieceli 07-22-2017 10:17 AM

Thank you everyone for your input on this. I appreciate the information. My car is all stock so I agree that the basic distributor with the 16 curve settings will be sufficient . I can do the pertronix thing but I like the idea of having something new and more likely reliable than what I currently have.

alfaparticle 07-23-2017 06:48 PM


To make a long story short, Tom prefers the programmable versions of the 123 over the earlier models with the 16 fixed curves.
I was sent a copy of Tom Sahines' curve by Mark Robinson - I have been advising him on his engine setup. The curve is similar to the "D" curve in the basic 123 except that it has 4 degrees less advance at idle. They are more or less identical above 2000 rpm. The practical consequence is that the throttle plates will be have to be opened a little more for the same idle speed compared to the "D" curve. That could be an advantage if you have an off idle lean spot that is caused by the throttle plate being a little behind the first progression hole at idle. Otherwise you will not be able to tell the difference.

I had my GTV6 on a dyno recently and I had a max advance of 30 BTDC as the starting point. It made 206 HP at the wheels. We advanced the ignition by 2 degrees ( easy to do with Megasquirt) and it made 212. We advanced it another 2 degrees and it made 214. I am unable to discern the change due to 4 degrees of advance when driving the car and I doubt that anyone reading this will be able to notice a difference between a "tuned" 123 and an appropriate canned curve in the basic distributor.

evieceli 07-23-2017 09:17 PM

Thanks everyone once again. I do appreciate all this very useful information. I emailed 123 distributors and they replied back telling me that their other website contained more information (which it did) instead of I didn't know that they had different websites... I thought it was strange that they wouldn't post the same technical data on the US website. Anyhow, they also said that for certain I can get a cap and rotor on my own but to be careful for fitment issues (in other words, check then double check when replacing anything.) Of course they sell caps and rotors that are 100% sure to be correct. In any case, this is what they sent me as their recommended alternative to buying their replacement parts:

Replacement Caps and Rotor for 123 Ignition

Borg Warner – Federated Auto Parts
Cap Rotor
8 cyl = 51-1860 8 cyl = 51-5731
6 cyl = C562
4 cyl = C520 4 and 6cyl. = D563P
Angled 4 cyl cap = GB463

Echlin – Napa Auto Parts
6 cyl = EP269 4 and 6cyl. = EP278
4 cyl = EP131
Old Style housing w/locating Tab VK105 Bosch 12355220560U or 03010
New Style housing w/locating Notch VK106 or BCH-1235522050
Angled 4 cyl cap = EP508 Will not fit on old style straight cap units w/o modifications.
The newer 2011 and up units have an adjustable locator tab on the 123.
Watch for fitment issues on the rotors. If you need oem, see

alfaparticle 07-24-2017 08:21 AM

When comparing a Pertronix upgrade to a stock distributor with a 123 consider the following:
The stock distributor has moving parts in the advance mechanism which will degrade over time - they may be degraded already. This will affect the advance curve.
Pertronix, like points has a fixed dwell angle. If you look at the coil current you see that at low rpm the current ramps up to max then stays at that value until the spark is discharged. That max current corresponds to saturation of the coil. Once that point is reached the coil current is turned into heat in the coil. As rpm increases the "plateau" shrinks until it just reaches saturation and the waveform has a sharp peak. Increase the rpm more and the height of the peak is reduced. That is the region where the energy in the spark is reduced.
the 123 distributor tries to control the dwell time rather than the dwell angle. At lower rpm it delays the start of coil charging to reduce or eliminate the current that only heats the coil. As rpm increases it increases the dwell angle in order to maintain that dwell time. It will continue to do this beyond the rpm at which Pertronix starts to deliver less spark energy. If you were to rev the engine high enough it would have to reduce the dwell time in order to leave sufficient time for the coil to fully discharge. I have not measured that rpm but I expect that it is North of 7500 rpm.
The bottom line is that the 123 will make stronger sparks than points or a simple points replacement at higher rpm and it will reduce coil heating at lower rpm.

GTVMk1 07-30-2017 08:37 PM

Had my car dyno'd this week following the 123 install.
I had the car initially setup on Curve #1, which to me seemed to work ok - albeit some throttle hesitation when accelerating from low revs. After much experimentation, the optimum curve for both low & high range revs was Curve #0 (1300-1600 motors), using max advance of 33 degrees at 5000 rpm. This gave a ruler straight 45 degree power line from idle to 4500 rpm. Instructions to the tuner were for usable torque, not max HP.
The mixture was initially very lean, which I believe was the result of changing the K&N pancake filters for a large single Pipercross unit. After replacement of the main jets, air correctors and idle jets, the AF/R was an ideal 12.5 to 13.4 through the entire rev range.
The car gained around 19 HP compared to last dyno and now drives beautifully.
The dyno tune is pricey, but I believe worth every cent.


alfaparticle 07-31-2017 08:15 AM

Did you try more max advance than 33 and if so, what did it do to your power curve?


ideal 12.5 to 13.4 through the entire rev range.
You have a very good carb setup. Would you mind posting it?


GTVMk1 08-07-2017 11:05 PM

Hi Ed,

When I spoke to the tuner on the day, he said that he tried the 40-43 degree advance suggested in the manual but the results were poor. The current settings are -12 deg at idle and -33deg at 5000 rpm.
Carbie set up is as follows:

Main jets are 115
Air Correctors are 185
Slow running jets are 50-F9


PS - For BB members in Sydney, I would highly recommend Tilley's Garage in Brookvale for your dyno tune.

Gubi 08-07-2017 11:49 PM

Man, that's crazy retarded at idle. But you can't fix that with the base 123. That's why the tune version is a better option.

Tom Sahines posted the below on the 750/101 forum. Note that the octane values he states are PON and are about 5 less than Australian RON.

I guess if it idles okay you're sorta fine, but -12 at idle is definitely suboptimal.

"I have evaluated the early 123 distributors and come to the conclusion that there are no good usable curves. The early 123 distributors simply copied many of the original Alfa curves which are no longer appropriate. Remeber that when those curves were designed pump gas was more like 95 octane vs the 91 octane we can get today. My dyno work has shown that with today's gas 36 to 38 degrees of total advance is optimum. Most all of the motors I build want to have 6 to 8 degrees of initial advance for a good idle and off idle performance. As noted when you add the 37 degrees of advance from the 123 built in curves you end up with about 44 degrees of total advance. At that level you will have engine knock and damage will occur. The only option is to use a high octane race fuel or set the maximum advance to 38 degrees and live with a crappy idle."

alfaparticle 08-08-2017 08:47 AM


My dyno work has shown that with today's gas 36 to 38 degrees of total advance is optimum
My dyno runs showed that 34 is optimum for my motor on pump gas.


As noted when you add the 37 degrees of advance from the 123 built in curves you end up with about 44 degrees
That is only correct if you choose an inappropriate curve. Tom Shaines suggested curve is similar to the D curve in the 123. I just has a little less advance below 2000 rpm.

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