Help installing MSD ignition

[kent olsen]

Ok before I install this MSD ignition I traced the existing wires.

The strange one is a fourth wire on the hot side of the coil!! Can't tell where it goes or why it needs to be there.

One wire goes to the tach, one to the points and one to the CD unit now where or what would need a trigger from the coil. Could this be left over from the previous Fuel Injection? I currently run webers so this should be your basic carburation/ignition setup.

Now if I remove this wire from the coil nothing happens!! It runs normally in the garage, haven't tried to drive it that way.

Anyone have an idea??

[Goth]

Not sure about your Pcar, but some cars run the hot through a ballast resistor and then to the coil at less than nominal voltage. Then they have a second hot from the starter solenoid to the coil that is only hot when the solenoid is sending power to the starter. This provides full current to the coil to help start the car & does nothing after that.

Hope this helps

[kent olsen]

Well I found something on the MSD instructions that say something about a trigger for the Fuel Injection so maybe that where it goes?

[Jeff Higgins]

It would help us to help you if we knew what car you have.

Wayne's book 101 Projects for Your 911 has detailed instructions for intalling an MSD 6AL on any 911. I followed those instructions on my '72 T and had no trouble at all. I think the article may be reproduced on this site's Tech Info Center, accessible through the tab at the top of this page. Check there; if you still have extra wires, let us know what you have and I'm sure some one can help.

[Goth]

I think this is the one Jeff was referring to:

Installing an MSD Ignition System

[kent olsen]

I guess that does make a difference!!

My car is a 1972 911T but with a 1974 2.7L engine. It had Solex carbs when I bought it with the 2.4 L engine and when I repaced that with the 2.7L I added Webers.

I'm not sure if this wire off the coil had anything to do with the Solex's or if it originally had FI but it doesn't seem to affect the car now when I take it off.

The MSD I'm installing is a Mallory also. Today I'm going to wire it up and see if it will run without removing the CD unit so I can switch back if I have a problem.

My next project is replacing the 2.7L with a 3.0L. I'm getting my shop set up to rebuild a 3.0L over the summer. I'm hoping for 230+ hp since the car has been gradually losing weight, down to about 2230lbs, that will give me the 10:1 pwr/weight I'm looking for.

Once we have a sunny day in Oregon, and I'm home, I'll post a picture of my car..

Kent Olsen
Aubergine cpe
72T upgraded 2.7

[kent olsen]

Well after carefully maping the wiring with the CD unit I hooked up the Mallory MSD. Everything worked as advertised, except the tach, so I removed the CD unit and wiring and permanently mounted the Mallory MSD. Tomorrow I'll regap the plugs and call Mallory to get the tach adapter.

Kent Olsen'
72t upgraded 2.7