View topic - Installing a Pertronix Ignition into a '41 DeSoto

Installing a Pertronix Ignition into a '41 DeSoto
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Author:  DeanMullinax [ Wed Feb 21, 2018 7:55 pm ]
Post subject:  Installing a Pertronix Ignition into a '41 DeSoto

I recently bought a 6 volt positive ground Pertronix Ignition system for my '41. We were about to install it when a friend of my mechanic asked if that system would throw off any of the electrical components that are used on the Simplimatic Transmission. He says the Simplimatic relies upon the timing of the opening and closing of the points. Hmmm... I have no idea and my mechanic wasn't sure either... so I ask the gurus in this forum if they might know. From what I read it sounds like it would be ok to use... but we want to be sure first!

If you have installed one on a '41 or a '42 with the Simplimatic, or even on an S-11 with the later semi-automatic, please let me know if it worked out ok. If it didn't, let me know that too!! All opinions will be appreciated.

I like the simplicity of the Pertronix set up and the benefits of having one, but am willing to definately for go this if its gonna cause a problem with the transmission shifting correctly.


Author:  TimBowers [ Wed Feb 21, 2018 10:21 pm ]
Post subject:  Re: Installing a Pertronix Ignition into a '41 DeSoto

Sounds like a good question for Pertronix Customer Service.

Author:  DeanMullinax [ Thu Feb 22, 2018 12:44 am ]
Post subject:  Re: Installing a Pertronix Ignition into a '41 DeSoto

Maybe.... but they make this version of the device for many different types of 6 volt positive ground systems. Don't know if they work on semi-automatics or not... I would think they would. Their disclosure simply said "fits 1941 DeSoto all models".

But when you get an electrician that puts doubt into your head you have to ask.

Was just hoping that someone might have had some experience with this or know for sure. That's what this board is all about right! :lol:

If nothing else... I might look into calling them as well.


Author:  BrentJacobsen [ Wed Feb 28, 2018 3:32 am ]
Post subject:  Re: Installing a Pertronix Ignition into a '41 DeSoto


I am assuming you still have the original M4 vacuum shift trans. According to the wiring schematics, the only electrical interaction between the transmission circuits and the ignition occurs during a downshift. A switch on the shift rail grounds the coil power through a resistor causing a momentary ignition kill during the movement of the rail. Killing the ignition momentarily unloads the synchronizers allowing them to disengage. I don't know how the Pertronix will interact with that.

I will give you a word of caution though. As a retired car engineer who lived through the introduction of car electronics, I can say that manufacturer's attempts to mount electronic ignition modules in the distributor were less than successful. The power transistor generates a lot of heat, and the distributor housing doesn't act very well as a heat sink. The result is a failed transistor or the circuit board they are attached to. GM HEI and Ford TFI are examples. The last issue of the DeSoto Adventures has a good story about that too. Breaker points are still available, can be replaced easily, and they give notice when they are in need of attention. Pertronix modules- not so much.

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