Twin plug, here's an idea

[Clark Griswald]

I've been toying with the idea of twin plugging my '86 for some time.

The conventional way to do this is use a dual 964 dizy with two coils and a "splitter" from andial. The splitter sits in front of the coils and duplicates the primary signal from the CDI to both coils.

Trouble is that Andial splitter is pretty expensive. I think I've heard it is the $600 range.

So why not use a pair of MSD 6A units with tach adapters. My understanding is the tach adapter provides a high impedence connection to be connected to the original coil primary leads. Since these are high impedence, why not just pop two in parrallel? Skip the Andial splitter.

Then the two MSD units feed seperate coils into the 964 dizy as normal.

So the solution requires the machine work, 964 dizy, wires, two msd units with tach adapaters and coils.

[911pcars]

Sounds reasonable. Theoretically (since I haven't done this), all you need is a means to deliver a separate high voltage circuit to each spark plug and you have the 964 distributor to do it. If you have the budget, you could purchase two digital ignition boxes and ign. coils from MSD, Crane (or ?) and have the ability to create a custom advance curve for the engine. Your ignition advance requirements will change anyway with the change to dual plugs.

If you use these independent units I don't see why the 964 sensor signal wouldn't be able to trigger them simultaneously. If the 964 sensor circuit doesn't permit this, use the Pertronix or Crane optical sensor to trigger the twin ignition boxes.

Nothing concrete, just brainstorming
Sherwood Lee
http://members.rennlist.org/911pcars

The MSD box can be triggered by any magnetic pickup.
They should have info on the web sight for different installations or you might just ask them how they would do it.
Just a thought
Chris

[Leland Pate]

Why not use the ignition brains out of a C2?


...nevermind...I'm so far out of my league here it's not even funny...

Very interesting topic though
Aren't MSD units about $350 a pop?
Two of them would be equal to the Andial spliter?

[Clark Griswald]

The MSD 6al is $130 at Summit. I got a brand new one on ebay for $100, which I am using on my truck with good results.

[Early_S_Man]

Chuck,

It might work, but you don't have a CDI-unit, or a magnetic pickup unit at the distributor to use on a 3.2 ...

The signal at the coil, controlled by the DME is +12 Volts and ground ... easily replaced by a ballast resistor for purposes of triggering a CDI-unit or MSD ...

[RLJ]

I think what you guys are talking about is called crank fire ignition. Some form of proxsimity switch is triggered by a slot or a magnet in a pulley or flange on the crankshaft. Lots of folks make those parts.

Randy Jones
1971 911 w/ twin plug up and running.