Wiring for 123 ignition - Alfa Romeo Bulletin Board & Forums
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post #1 of 59 (permalink) Old 09-14-2019, 07:47 PM Thread Starter
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Wiring for 123 ignition

Do I have it right?


My 1973 spider is a negative earth car, correct?




Therefore

Red wire from 123 ignition to positive on coil

Black wire from 123 ignition to negative on coil


Green wire from firewall to negative coil


Is that all?




Will a flame thrower coil work with a 123 ignition?

Does the coil itself need a ground wire going from the negative to the body?

Thank you all very much in advance!
I seriously appreciate all the help!

Last edited by tremere613; 09-14-2019 at 08:23 PM.
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post #2 of 59 (permalink) Old 09-15-2019, 02:57 AM
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Quote:
Originally Posted by tremere613 View Post
Green wire from firewall to negative coil
No! Your drawing clearly shows power supply to coil to positive connector!
Green/black wire (from ignition switch) needs to be connected to +/15 @ your coil.

Quote:

Does the coil itself need a ground wire going from the negative to the body?
No.

R.I.P. Alfa Romeo 1910 - 1986. 1987---> Badge engineering since then.
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post #3 of 59 (permalink) Old 09-15-2019, 09:20 AM Thread Starter
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Quote:
Originally Posted by hunttheshunt View Post
No! Your drawing clearly shows power supply to coil to positive connector!

Green/black wire (from ignition switch) needs to be connected to +/15 @ your coil.







No.


Thank you! Previous owner had it wired incorrectly, I was wondering why he stated I would need to “figure out ignition”.

As for spark plug wires, am I right in assuming the longest wire goes closest to the firewall and the shortest closer to the radiator?
Very obvious I know! Just making sure..


In addition how do I determine which spark plug wire goes into which port on the distributor?

Thanks for the help!
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post #4 of 59 (permalink) Old 09-15-2019, 09:30 AM
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That looks like a Flame Thrower 2 coil. If that's the case then it's 0.6 Ohms and won't work properly: the 123 requires minimum 1 Ohm primary coil resistance. It's also sideways mounted, and that's not recommended for liquid-filled coils.

A proper coil in the Pertronix line would be the Flame Thrower 40611. It is 3 Ohms and epoxy-filled.
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post #5 of 59 (permalink) Old 09-15-2019, 09:39 AM
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Quote:
Originally Posted by tremere613 View Post
In addition how do I determine which spark plug wire goes into which port on the distributor?
- take out plugs # 4 and # 1
- do turn your motor clockwise by pushing forward in 5th gear (WITHOUT having ignition ON !! It must be OFF !) until your arrow indicator on your front cover points to TDC on your pulley
- then take a flashlight and lighten into plug hole. You´ll either see on
cyl. #1 OR on cyl. # 4 both valves slightly off seat. That´s the cylinder which you WON´T connect to the plug lead in that moment your rotor is pointing to on your dizzy to a specific port at your cap. You do connect that lead to the other one (means # 1 OR 4 !). Then start fitting the other plug leads clockwise from that one you´ve already fitted after indicating either in order 3-4-2 (when you´ve indicated the first lead going to cyl. # 1 - which is next to water cooler) OR 2-1-3 (when #4 was at TDC before)

OR: Take off valve cover, turn engine to TDC # 1 (cam lobes pointing both to the outer sides !), and start then with cyl. #1 / dizzy rotor pointing in that moment to a specific port in your cap.

R.I.P. Alfa Romeo 1910 - 1986. 1987---> Badge engineering since then.

Last edited by hunttheshunt; 09-15-2019 at 11:53 AM. Reason: Changed term "torch" against "flashlight" ;-)
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post #6 of 59 (permalink) Old 09-15-2019, 10:39 AM
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Quote:
Originally Posted by hunttheshunt View Post
- then take a torch and lighten into plug hole...
a few years back, I once advised someone to look inside the gas tank with a torch...........luckily they didn't!

In the USA a 'torch' is a butane torch or a blowtorch.
They use the word flashlight.

Dom - Alfa Spider 1990 S4 - formerly: Alfa 101 Sprint, 2600 Sprint, Montreal - family classics: Jensen Interceptor II, '58 Hooper RR Silver Cloud I, Shadow II, '60 Corvette.
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post #7 of 59 (permalink) Old 09-15-2019, 11:06 AM
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Quote:
Originally Posted by spiderserie4 View Post
a few years back, I once advised someone to look inside the gas tank with a torch...........luckily they didn't!

In the USA a 'torch' is a butane torch or a blowtorch.
They use the word flashlight.
Thanks, Domi - I´ve corrected it.

R.I.P. Alfa Romeo 1910 - 1986. 1987---> Badge engineering since then.
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post #8 of 59 (permalink) Old 09-15-2019, 11:15 AM Thread Starter
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Quote:
Originally Posted by spiderserie4 View Post
a few years back, I once advised someone to look inside the gas tank with a torch...........luckily they didn't!



In the USA a 'torch' is a butane torch or a blowtorch.

They use the word flashlight.

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post #9 of 59 (permalink) Old 09-15-2019, 11:24 AM Thread Starter
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Wiring for 123 ignition

Quote:
Originally Posted by hunttheshunt View Post
- take out plugs # 4 and # 1
- do turn your motor clockwise by pushing forward in 5th gear (WITHOUT having ignition ON !! It must be OFF !) until your arrow indicator on your front cover points to TDC on your pulley
- then take a flashlight and lighten into plug hole. You´ll either see on
cyl. #1 OR on cyl. # 4 both valves slightly off seat. That´s the cylinder which you WON´T connect to the plug lead in that moment your rotor is pointing to on your dizzy to a specific port at your cap. You do connect that lead to the other one (means # 1 OR 4 !). Than start fitting the other plug leads clockwise from that one you´ve already fitted after indicating either in order 3-4-2 (when you´ve indicated the first lead going to cyl. # 1 - which is next to water cooler) OR 2-1-3 (when #4 was at TDC before)

OR: Take off valve cover, turn engine to TDC # 1 (cam lobes pointing both to the outer sides !), and start then with cyl. #1 / dizzy rotor pointing in that moment to a specific port in your cap.


Thank you for the write up!

Is this correct?





More reference material for when I tackle the ignition:


Last edited by tremere613; 09-15-2019 at 11:29 AM.
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post #10 of 59 (permalink) Old 09-15-2019, 11:53 AM
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Forget the last picture; should a PO have already changed the oil pump, then the pointing direction of rotor COULD be different; just follow the instruction to find No. 1 and then start fitting clockwise the other 3 leads.

Your 1-2-3-4 picture is correct. But firing order is 1-3-4-2.

R.I.P. Alfa Romeo 1910 - 1986. 1987---> Badge engineering since then.

Last edited by hunttheshunt; 09-15-2019 at 10:03 PM.
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post #11 of 59 (permalink) Old 09-15-2019, 12:27 PM Thread Starter
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Quote:
Originally Posted by hunttheshunt View Post
Forget the last picture; should a PO havd changed already your oil pump, then the direction of rotor COULD be different; just follow the instruction to find No. 1 and then start fitting clockwise the other 3 leads.



Your 1-2-3-4 picture is correct. But firing order is 1-3-4-2.


Thank you!!
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post #12 of 59 (permalink) Old 09-16-2019, 08:28 AM Thread Starter
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Originally Posted by Gubi View Post
That looks like a Flame Thrower 2 coil. If that's the case then it's 0.6 Ohms and won't work properly: the 123 requires minimum 1 Ohm primary coil resistance. It's also sideways mounted, and that's not recommended for liquid-filled coils.

A proper coil in the Pertronix line would be the Flame Thrower 40611. It is 3 Ohms and epoxy-filled.


Thank you so much! You probably saved me hours of troubleshooting!
Will any of these work by chance?

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post #13 of 59 (permalink) Old 09-16-2019, 08:43 AM
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Quote:
Originally Posted by tremere613 View Post
Thank you so much! You probably saved me hours of troubleshooting!
Will any of these work by chance?

Do not try to 'save' 30 bucks.
Buy a NEW one!

R.I.P. Alfa Romeo 1910 - 1986. 1987---> Badge engineering since then.
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post #14 of 59 (permalink) Old 09-16-2019, 09:42 AM
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For best performance use a 0.6 ohm coil with a 0.6 ohm ballast resistor. I posted simulations for the relative performance of that setup compared with a 1.5ohm and a 3 ohm coil. The 0.6 makes much more spark energy above 3000 rpm due to the lower inductance of the 0.6 ohm coil. MSD supply a suitable ballast resistor with a new Blaster 2 coil.

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post #15 of 59 (permalink) Old 09-16-2019, 09:47 AM Thread Starter
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Wiring for 123 ignition

Quote:
Originally Posted by alfaparticle View Post
For best performance use a 0.6 ohm coil with a 0.6 ohm ballast resistor. I posted simulations for the relative performance of that setup compared with a 1.5ohm and a 3 ohm coil. The 0.6 makes much more spark energy above 3000 rpm due to the lower inductance of the 0.6 ohm coil. MSD supply a suitable ballast resistor with a new Blaster 2 coil.


Would the ballast resistor depicted on my second picture work with my current flamethrower?



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