Spark with or without transistorized ignition

[bracurrie]

Contemplating installing a 123 dizzy on my M130 where it has a transistorized ignition. Besides the lower current through the points does the ICM also provide a hotter spark?
If installing a 123 can you keep the hotter spark?
Brad

[jeffc280sl]

I think you will find your answer here.

https://www.sl113.org/wiki/Electrical/TransistorIgnition

Generally speaking the ignition coil determines a hotter or cooler spark plug current

[bracurrie]

Very good write up on the transistorized ignition. I had read that before but it doesn't really say that the spark is hotter, through I know it is.  However, I will reach out to 123 and see if the transistorized system and the hot spark can stay when the system is installed. Brad

[jeffc280sl]

Please look at the attached simplified picture of a transistorized ignition system.  The ignition components sit on one side of the coil. It provides a low voltage pulse to the coil where it is amplified/multiplied and sent to the distributor.  The distributor does what its name implies and takes the high voltage input from the coil and sends it to the spark plugs.   There are various coils available for our cars to provide hot or cooler high voltage inputs to the distributor.  I believe I have the bosch blue coil on my car.

[Tyler S]

The transistorized ignition is just that. A transistor that acts as a set of points to switch the coil on and off and in turn puts less wear and stress on the points in the distributor. The 123 has its own transistor and optical pickup built in so you would not keep the original transistor ignition box connected as there would no longer be points or a signal for it to use. Another member successfully  kept the speed relay and emissions gear intact and functional using a resistor in series from the coil. See post:#19 of link below.
https://www.sl113.org/forums/index.php?topic=29725.msg215309#msg215309

[Shvegel]

Save all old parts.  Very tough to find.  I ended up having to fabricate the ignition box mount under the battery because the only person that had one wanted $300 just for the piece of bent sheet metal.

[bracurrie]

The transistorized ignition is just that. A transistor that acts as a set of points to switch the coil on and off and in turn puts less wear and stress on the points in the distributor. The 123 has its own transistor and optical pickup built in so you would not keep the original transistor ignition box connected as there would no longer be points or a signal for it to use. Another member successfully  kept the speed relay and emissions gear intact and functional using a resistor in series from the coil. See post:#19 of link below.
https://www.sl113.org/forums/index.php?topic=29725.msg215309#msg215309

Coming into focus for this amateur here. Shame I bought another ICM when I won't need it after installing 123 dizzy.
What I am unsure about now is maintaining hotter spark that the ICM facilitates on the OEM setup. 

[Tyler S]

Brad, get yourself a high output coil to pair with the 123 and it will surpass the factory Ignition system. Remember its the coil doing all the work. The distributor/ICM is just the component controlling it. The 123ignition website has a few options they recommend.
I have a Bosch red coil paired with my 123. There is a “flame thrower” coil that outputs 40kv. I have this coil installed in my 1936 Ford Flathead. Couldn’t be happier.

[bracurrie]

Tyler,
Thank you for the reply. I plan on trying the coil that I already have when I get a 123.
Brad