twin plug ignition switchs

[ficke]

I finally installed my twin plug switches.
I had both CDI box's wired through the ignition switch on the key, after learning the hard way why race cars with twin ignition and airplanes with twin ignition have two switches, to test each circuit, I finally wired two switches in after the key switch.
Now I can tell very easily if I have a fouled plug or??
I found NOS German push pull switches very similar to the RSR ones Porsche used reasonably priced at a vintage motorcycle parts site.

[jsveb]

Very very nice.

Could you share more details on how to do this?

Twin plugging is in my future, heads already prepped.

[ficke]

Thanks, jseveb, I just copied what I saw on Porsche 906, twin cam street cars and period race cars with twin plugs.
On the street cars Porsche ran the power to the isolator switches first though the key switch then to the isolator switches.
So I wanted to find switches like the OEM ones of those cars.

I saw new ones pretty cheap, $9.00 and reproduction ones for $100
I finally settled on these
GenuineNOS
quality was good and they looked right.

[wayner]

Do you have any reference pictures to the switch placement in the actual race cars?
I've never noticed them before but am interested.

[911tracker85]

interesting. one more item on my list for the 930 project...

[wayner]

I just answered my own question:

Here is a pic of them below the gauges (just above the ignition key)
This is a 1973 RSR

Interestingly, these seem to be very similar to what was used in 1955 on the 550 spyder twin cam.



This one is a replica I think, but you get the idea ( next to the ignition key), but in the 550 spyder, a switch turned not the ignition while the other turned on the fuel.

[ficke]

Here is a 914/6 race cars isolator switches for the ignition

[wayner]

I just picked up these at Princess Auto

Similar to what Ficke has but the bezels are different.

They look much bigger in pictures though. I'll size them up in the car and see if they look appropriate. The head is less than the size of a dime and about twice the size of the winder on my watch. (I suppose this would be easier to describe if I had a tape measure handy )

P.S.
Thanks for starting this thread. Very timely for my build.

[onboost]

Fick,
Did you use something existing that was previously wired your car, or did you make/build a harness.. share diagram?

[ficke]

Originally Posted by onboost

Fick,
Did you use something existing that was previously wired your car, or did you make/build a harness.. share diagram?

My car was twin plugged in 1986, it is running two 6 pin Bosch CDI box's and a Andial dist.
To wire in the isolator switches I just ran three wires from the engine compartment to the center counsel, where I mounted the two isolator switches. One wire is the hot wire (5) that was used to fire both CDI box's that is energized by the key operated ignition switch, the other two or now the ones that get hot by my isolator switches and are now connected to the CDI box's (5).
Here is a link that explains the connectors on the Bosch 6 pin CDI box.
How to test a 6 pin CDI ?