MSD ignition related questions
 

Hello all:
car: Recently purchased 1986 Porsche 911 3.2

I just installed the MSD 6425 6L ignition, along with its mating MSD blaster coil. The car stared, no problem, though I have not taken it out for a test drive. I have a couple of fundamental questions, which I hope someone could help.

1. I understand that this model car has a CDS (capacitor discharge system)unit. As I also understand, the MSD is also a CD unit. So, since I just removed to original coil and replaced it with the new coil, and installed the MSD unit, would mean that I have a CDS unit piggy backing on another VDS unit? does it make sense?! how does it work? Is it really healthy to put the MSD in this model 911. I have had an older model in my 911 SC, which has been working beautifully, ever since it had been installed.

2. Is the distributor in this car electronic?

I would appreciate any and all feedback.
Cheers,
Zack

NO, the 84-89 cars have basic inductive coil it is not CDI.
I see no reason to install a MSD in the 84-89 cars unless you are forced induction like Turbo or Super Charger.

The distributor is just mechanical and has no electronics in it. It does have springs for rotor phasing. But timing the coil events is done entirely by the ECU. Within the ECU it has a large darlington transistor that simply grounds the coil's '-' post to charge the coil. Dwell times are also fully controlled very accurately by the ECU.

My advice is don't bother with MSD as a matter a fact I've seen several MSD boxes induce tons of noise into the factory ECU and cause worse issues. Why did you decide to go with MSD?

Dear Scarceller
I thank you very much for your through explanation, I now completely understand what is going on; thanks again
As for your question why I decided to install on this car is that I had one installed in my 1989. 911 SC and the car works beautifully; the car starts even on the first tiny movement of the crank and performance is just fantastic. moreover its installation is highly recommended in the book 101 projects for your Porsche 911!

So, that is why I decided to install the MSD on there 911 3.2; of course now I have my doubts whether I really need it in this car unfortunately this came to after having spent nearly $400

The MSD may be giving you better ignition spark than the stock unit, so I would not discount it as being a bad move.

If you are not getting RFI or other interference I would leave it in. You can also put a filter cap in the +12 line.

I don't have any MSD experience, but I did put a Daytona-sensors CD-1 in my 1973 2.7 with MFI and the start and performance is much better than the stock Bosch CDI. I know this is not the same as your car, but a good aftermarket CDI can do wonders in an early Porsche.

But the installation has to be right with good 12 vdc, ground, etc.

In addition to better spark you can also have and electronic timing curve, soft rev limiters, data logging and much more in a good aftermarket system.

Sorry for silly question:
What is the best setup would be for '74 2.7L with webers?
Thank you

Partsklassic makes a very nice setup for early cars. They put modern electronics inside the Bosch CDI box and their coil is visually the same as the original.

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I have an older msd 6A in my 2.2 made into a 2.7 with webers and it works very well. I can't put rev limiters in this model and have but haven't hooked up the msd tach adapter yet so my tach will work again so chances are that would need addressed in your 2.7 as well if you go msd. I also have the msd coil installed.