MSD, Pertronix and the speed switch...

[Tspringer]

Hoping to actually get to tuning the hotrod this weekend! If the corrected struts come in from SRP that is

I have the car running with the MSD setup. The tach does not work but that will be solved shortly. Palo Alto speedometer is replacing the board in the early tach and sending it back so it will work just plugged in from the MSD tach output.

Next is upgrading to the pertronix ignitor to eliminate the points. I am installed a new distributor cap and a set of magnecore plug wires at the same time. I have the MSD 6AL and MSD blaster2 coil both of which are new.

Currently, the black/purple wire that normally attached to the CD box from the speed switch for the MFI is not attached to anything. Not an ideal situation for a smooth running MFI system. My understanding is that this wire needs to be connected to the points in the distributor. Originally it shared a connection at the CD box with the wire running from the points to the CD box, thus it was getting a signal from the points.

The MSD white wire is now running to the points alone. I was going to attach the speed switch black/purple wire to the points along with the MSD white wire.

Now that I am going to eliminate the points with the pertronix... Im not sure how to wire it up. I know the speed switch needs a "points" signal and the MSD also requires this... but with a pertronix replacing the points how is this best solved?

Anyone with MFI, pertronix and MSD dealt with this and know exactly how to wire it. I am getting some diagrams from the pertronix website and MSD on wiring those two together, but of coarse they dont tell you how to wire in the speed switch.

Thanks for the help! I hope to have some "final" pics of the project to post this weekend!

[Tspringer]

Here is a quick link to the pertronix instructions for installing with the MSD:

http://www.pertronix.com/

dang, it wont link directly to the diagram. go to support, then troubleshooting tips and then the MSD link. Its an acrobat diagram that I dont know how to paste into a post here.

I would plan on wiring the speed switch to the shared white MSD / ignitor black wire. If I splice the speed switch in here.... will the it work properly?

[Jay Zollinger]

I think that the black/purple wire is actually the lead from the tach--it may go through the speed switch, but I wasn't aware of that. In my '73 S with the stock CD unit, the black wire from the Pertronix unit is tied into the black/purple tach lead and the black wire from the CD box with a two-way spade connector. The red wire from the Pertronix is hooked directly to one of the three fuses in the engine compartment (I think it's the bottom one).

[Tspringer]

There is a black/purple wire that runs to the tach. On my car there is also a black with purple stripe wire that runs from the speed switch and through a connector to a black wire and to the CD box. It connects through a dual connector to the CD box at the same point as the black wire running from the points inside the distributor.

Wiring up the pertronix with the MSD isnt the question really.... its where this wire from speed switch needs to be incorporated into the circuit?

Anyone know the answer?


Thanks!

[Tspringer]

bump..... going to tackle this in the morning.

[Early_S_Man]

Terry,

Here is the MSD-Pertronix diagram, and the speed switch/RPM Transducer needs the same trigger as the MSD, so it should go to the Ignitor White/MSD Black wire junction.

[Tspringer]

Thanks Warren. I thought that was the case, but it seemed a bit to obvious. I was worried it would somehow screw up the speed switch.....

I'll wire it all up tomorrow like that. Also have a bigger problem now with a nasty grinding noise when driving under power.... see the seperate thread.