Technical Installing a 123 ignition - Log and steps

[rmribeiro]

Hi,

I just purchased a new 123 ignition distributor to replace my current distributor that keeps getting me into trouble ( point blew, condenser also and most recently the rotor also broke ).

So I created this thread to document the steps and parts. Hopefully it will help others in this process in the future.

My car is a Fiat 500F from 1967 that I think that has a distributor from a 500R.

References that I have compiled to go thru the process:

- Fotos of it assembled and discussion on the spacer for different types of engines:
https://www.fiatforum.com/500-classic/475346-installing-123-distributor.html
https://www.fiatforum.com/500-classic/461949-need-help-123-ignition.html?461949=#post4353054

- Good discussion of the settings and curves:
https://www.fiatforum.com/500-classic/446671-more-questions-about-setting-123-ignition.html

- Official Online manual :
http://www.123ignition.se/pdf/FIAT2R.pdf

- Short answer about how to install it:
https://www.fiatforum.com/500-classic/446518-123-ignition-static-advance-question.html?446518=#post4232929

"The simple answer is that you fit and set the 123 at TDC.
For simplicity, before you take out the old distributor turn the engine until the rotor points towards either No.1 or 2 plug lead on the rotor cap.
Set the TDC mark on the pulley to align with the TDC arrow on the timing cover (some later engines have several marks).
You fit the new distributor so that its rotor faces appproximately the same direction.
Then do the green light thing as per instructions.
Although it is set at TDC the distributor is actually electronically at 10 degrees BTDC. As soon as it starts to revolve its little brain puts on the correct advance at any given speed or setting.
I was sceptical at first about using a strobe, but after that, ideally you should check that at higher revs, the sparking is actually at 18 degrees."​

I will post pictures and step by step of my process. Hopefully without making a mess.

Any recommendations from your past experiences are appreciated.

 

[rmribeiro]

Here are the photos of both the ignition coil and the distributor.

Strangely there is a hole at the bottom that is threaded but there is nothing there and it seems to be open to the inside so it might be something wrong with it. I think water can get in thru that hole. I will ask the seller before installing it.

 

[fiat500]

Here are the photos of both the ignition coil and the distributor.

Strangely there is a hole at the bottom that is threaded but there is nothing there and it seems to be open to the inside so it might be something wrong with it. I think water can get in thru that hole. I will ask the seller before installing it.

At the bottom of the hole you will see an Allen-head screw. When this is removed, and with great difficulty, you will see a rotary switch which is actioned by a long, thin, flat-blade screwdriver. This is what selects the different ignition curves that you will read about in the instructions.

See: https://www.fiatforum.com/500-classic/483054-123-ignition-profiles.html?p=4558119

 

[rmribeiro]

I now have information about "the threaded hole". It is there to give the possibility to attach an additional cable to ground in case the ground between the engine and the chassis is not good. If you have a good ground between engine and chassis, just leave it open.

 

[fiat500]

I now have information about "the threaded hole". It is there to give the possibility to attach an additional cable to ground in case the ground between the engine and the chassis is not good. If you have a good ground between engine and chassis, just leave it open.

Can you post an image of that please?

 

[rmribeiro]

I already did. It is the 3rd picture:
PXL_20201117_215427801.jpg (3 of 8)

 

[rmribeiro]

By the way you can also see it on the last picture :

Yesterday I assembled everything but could not get the car to start.

I will post some pictures of the process.

I will need to start a diagnostics process now. Not sure where to start.

 

[rmribeiro]

Rechecked the connections everything seems good.

Measured 11.6v between both poles of the ignition coil.

11.6 between positive pole and outer shell of the distributor. So ground seems to be good.

Voltage of the battery is not at its highest nso I tried with another battery and did nit start.

I am having no sign of the ignition while trying to start the car.

If I rotate the engine by hand I can see the green light on the distributor turn off and on.


When I installed the ignition I also installed a new coil. Bosch blue. Could it be faulty?

How do I teste that the distributor is doing its job?

 

[fiat500]

How do I teste that the distributor is doing its job?

The distributor is very tough and will still work at that voltage.

Are you certain that the green LED lights at exactly TDC and that at that point the rotor-arm points directly at the HT wire for the cylinder which is on the firing stroke, ie. valves closed?

Is the red lead connected to + on the coil and the black to the - ?

If so, it may just requre the distributor to be turned one way or the other by a few degrees.

 

[rmribeiro]

Are you certain that the green LED lights at exactly TDC and that at that point the rotor-arm points directly at the HT wire for the cylinder which is on the firing stroke, ie. valves closed?

I will check, most of time the light is on I think turns of a little before the TDC. Is the light the equivalent of points? Green closed , off open?

Is the red lead connected to + on the coil and the black to the - ?

Yes. What I am not sure is if the car engine has a good heath, but it should as it was working before.

I have checked this video. It has some instructions to test a similar system:
https://www.youtube.com/watch?v=Y3SrWpUTPfM

 

[fiat500]

I will check, most of time the light is on I think turns of a little before the TDC. Is the light the equivalent of points? Green closed , off open?

Set the engine at exactly TDC and don't move it.
Assuming the rotor-arm is accurately aligned so that it faces the correct, firing HT lead, turn on the ignition and loosen the distributor..
If the LED is off, slowly turn the distributor anti-clockwise until it just illuminates; if it is already on, turn the distributor clockwise until it goes off and then do as described above.
Secure the distributor.
The light is not exactly the same as the points because it is used to align the distributor. The internal microchip then causes the spark at the correct point relative to engine speed.

 

[rmribeiro]

Question:

If I understood correctly if I put a multimeter to measure the voltage between the red and black , with the red wire connected to the battery I should see:

0 V when open state ( 18 degrees after the transition from on to off (TDC) )
12 V every other position.

Is this correct?

 

[fiat500]

Question:

If I understood correctly if I put a multimeter to measure the voltage between the red and black , with the red wire connected to the battery I should see:

0 V when open state ( 18 degrees after the transition from on to off (TDC) )
12 V every other position.

Is this correct?

I don't know. Unlike with contact-breakers, the internals of the 123 aren't simply making and breaking a circuit at a regularly defined interval. Depending on the"curve" chosen, the spark will always be be activated at the "perfect" moment BTDC. This moment will vary according to the rotation speed of the distributor.
So I don't think you will prove anything with the multimeter. In fact, when initially setting the LED, the black wire should not be connected.

 

[rmribeiro]

Today I was able to check:

1- The ignition coil is working. At least it lights up the sparkplug tester.
2- The distributor seems to be working because the sparkplug tester is blinking
3- The markings on the flywheel are at TDC
4- Learned that TDC mark is fore both cylinders. When I rotate manually starting at TDC for cylinder 1 the rotor is pointing to cy1 , next Time TDC aligns the rotor is pointing to cy2 and so forth.

So the problem must be related to some problem with the setting up process and finding the right alignment of the ignition.

The instructions says that in the beginning of the process the green light should be on. In my case it is off, I have ro rotate slightly anti clock wise for the light to turn green.

I could not get the car to start and now the battery is dead. So I have to wait until it charged again.

 

[Veloman518]

So I just installed the same 123 unit on mine recently. My original coil was wired wrong but a stock distributor will run with the ignition switch feeder wire to either the negative or positive terminal of the coil. It’s supposed to have the feeder on the positive terminal though. This creates the correct spark. When you put the electronic ignition on, make sure the feeder from the ignition switch goes to the positive terminal of the coil and then connect the 123 as instructed. Should fire right up if everything else is even close.

 

[rmribeiro]

My instruction manual says that :

1 - Turn ignition key on
2 - Turn dist. clockwise until led goes out
3- turn if back until the led lights again

but when I turn on the ignition key the led is already off...

 

[fiat500]

My instruction manual says that :

1 - Turn ignition key on
2 - Turn dist. clockwise until led goes out
3- turn if back until the led lights again

but when I turn on the ignition key the led is already off...

...therefore turn the distributor anti-clockwise until the LED just lights up.

 

[rmribeiro]

Will do!

I think I tried rotating clock wise until it light up and then off again. But that was a week ago and battery was very low so I could only get 4 turns of the motor before it died. Charged up the battery and hope to get some time to try again soon.

Now that I know which way to turn I have a lot less combinations to try.

Thanks!

 

[rmribeiro]

Finally I was able to start the car! And it looks like it is running good.

Tried the full diagnostic to check every component:

1 - Took out the plug and checked for spark - It was ok
2 - Changed the coil back to original and tested - Had spark in the plugs

So if I have spark in the plugs it was a matter of getting the timing right.

Tried to wiggle the Dizzy around while cranking but could only get some puffs or when I turned it too much anti-clockwise I would backfire on the exhaust ( flames and all coming out )

Took everything out and assembled everything with extreme care.

1- Found TDC by taking out the plug ant putting a screwdriver to find the momment it was at the TOP. There is a window os some degrees between reaching the top and starting to come back down. So I set everything to the first moment I felt the screw driver stoped moving up.

2 - Checked the markings on the pulley. Because I am looking from above depending on the angle you have 1 or 2 degrees of rotation that can look like TDC.

3 - Using extreme care I marked the middle of the rotor arm to align with the cap on cylinder one. They should already have these markings on the device, but I put it in using a pen to make it easy.

4 - Slid the distributor in very carefully not so not to loose the alinement on point 3. I think this is critical for the success because when you put it in there is slight rotation due to the fact that the teeth are not perpendicular.

5 - Because the ligh was off I had to rotate the distributor anticlockwise for the light to turn on. Not much it was just a little nudge, maybe 1 degree or so.

6 - tightened the screw and connected everything

7 - Started the car without choke but had to press the fuel pedal a little.

Next steps:

- Put everything in its place. Route the cables thru the back of the engine compartment. Put some thermo retractable insulator at the critical points and connections.

Take the car for a spin to test it out.

I will post pictures of the final assembly.

Thank you for your help!

 

[rmribeiro]

Quick update.

I have now put 200km on the little FIAT and everything is perfect. Now the car starts without choke or very little choke, runs very stable. Idle is perfect with no oscillations.

Only quirk, that I already had and did not go away is that going downhill sometimes I get some blowouts (?) out of the exhaust.