Ignition box options

[icecube76]

My 75 911s came with a crane cams xr700, and an american autowire wiring harness.
I am thinking of replacing the ignition box to something better.
What options do I have?

[darrin]

is it causing you any problems/issues?

[LJ851]

Oh boy, here we go.

[Joe Bob]

oem stock or a headache.....

[icecube76]

Originally Posted by darrin

is it causing you any problems/issues?

No no problems. I thought I should upgrade ,since the box is 10 years old.

[icecube76]

Originally Posted by Joe Bob

oem stock or a headache.....

I am not sure how to connect the oem box. It's not the original harness.

[Joe Bob]

Mid year Porsches.....if it ain't broke ignore it. Get a Bentley manual and follow the wiring diagram.

[Walter_Middie]

icecube76,

Joe Bob and LJ851 are being pretty elusive - let me see if I can translate for you:

Oh boy, here we go.

Years ago, I posted that I "upgraded" my stock Bosch CDI with a "modern" MSD box when I was having ignition issues. I was severely chastised for thinking that the MSD box was somehow better or more modern. The general thinking is that the stock Bosch unit is every bit as good, or better, than the "modern" replacements. I still have my MSD, and I love it - but I no longer think of it as an upgrade - it just works.

The original wiring for a mid year has a 3 pin CDI box. Later SC cars have a 6 pin CDI box.

There are 3 wires going to the original CDI unit, two white wires and a red one.

• One white wire goes to the + coil (or transformer) terminal.
• The other white wire goes to the distributor points and the tach.
• The red wire is +12 volts switched through the ignition switch on the dashboard.

[HaroldMHedge]

Here are the XR700 Instructions. Using Rex's guidance and if needed the factory wiring diagram and the installation instructions you should be able to figure out the changes made to the factory wiring.

The X700 is now made by FAST Fuel Air Spark Technology.
XR700 Power Module

Summit Racing has a copy of the old instructions on there website.
Fireball Installation Instructions for XR700 and XR3000
https://static.summitracing.com/global/images/instructions/xr700%20instructions.pdf