Help Tune Up Gone Bad!

GB73911 · 10-17-2006, 05:06 PM

I have a 73 911T with 6 pack Webers on a 2.4L engine. I just put a Pertronix ignition, MSD blaster coil, new plugs and Clewett plug wires. The car turns over but will not start. However, when I turn on the ignition it does turn over, but won't catch. When I turn off the ignition it trys to catch.

The Pertronix has are two wires - red and black. The black is attached to the negative on the coil. The red is connected to the wiring harness to connection with a purple wire with a black stripe and a black wire. I also reattached the red wire from the original coil to the positive post and to the coil bracket.

I have 8 to 9 volts from ignition system to the distributor.

Everything is attached exactly as removed. Any help? Do I need to purchase a MSD box to finalize the setup and attach the MSD coil?

Any help greatly appreciated.

GB73911

rsscotty · 10-17-2006, 06:54 PM

You never mentioned if you are using the OEM Bosch CD box in conjuction with you newly installed Pertronix and Blaster coil.

In the mean time, I would not try to start you car until the wiring issues and parts compatibility are resolved.

If you have the Bosch CD installed with the OEM coil...the red wire from the Pertronix goes to a 12volt switched supply..most likely at the small fuse panel in the engine compartment. The black wire from the Pertronix goes to the black and purple wire and also the black wire that originally went to the points at the distributor.

The Blaster 2 coil should be used with a MSD 6AL CD box..not with the OEM Bosch CD box.

If you are not using the factory CD box, then things are still wired differently if you chose to use the Blaster coil.

2.7RACER · 10-17-2006, 07:52 PM

GB,
As rsscotty said the red wire from the pertronix must be attached to a switched 12 volt supply.
The black wire connects to the wire which goes to pin C of the CDI box.
The wire going to the CDI box is shielded. You need the inside wire to the black wire of the pertronx.
Go to pin C and determine the wire color, then check the other end with a ohm meter to make sure what looks like it goes to the CDI box actually does.
The shield goes to ground. Either the negative side of the coil or ground at the fan housing where the coil is mounted.
From the CDI box pin A is the output, which goes to the positive terminal of the coil, terminal 15.
Same story, make sure whatever color is at pin A of the CDI box goes to terminal 15 of the coil.
Terminal 1 of the coil goes to ground, same place as the shield.
With 12 volts at pin B of the CDI box, you are going to get spark to your plugs.
Just time it up and enjoy.

GB73911 · 10-17-2006, 10:57 PM

rsscotty:

I am trying to use the OEM Bosch CD box. Would it be better to incorporate the MSD-6200 CD Syystem?

2.7RACER:

Obviously I'm new at this and interested in learning. Where is pin A, B & C located and is there a schematic for the OEM CDI box in the tech info center?

As you can tell from the time of my reply my problem is on my mind. Hopefully I'll have this all corrected be this afternoon. I'll e-mail and let you know.

Thanks,
GB73911T

2.7RACER · 10-18-2006, 07:09 AM

GB,
Yes there is a schematic for your car in the tech info center.
After you select the Tech Info tab, you'll see a features box to the left.
The electrical diagrams are located there.
It will take a little looking to get familiar with the layout.
The CDI box in your car has a three pin connector attached to the bottom of the box. If you remove the connector you'll notice the pins are identified as A,B and C.
A is the output and goes to the positive terminal of the coil, pin 15.
B goes to switchable 12 volts. This is the power for the CDI box.
C is the input from the Pertronix via a shielded wire.
The ground is located at the CDI box next to the three pin connector.
The shield goes to the ground.
You may find another wire either at the distributor or near the CDI box that goes to the Tach. It is also connected to the black Pertronix wire.
Enjoy,

rsscotty · 10-18-2006, 07:28 AM

GB73911

There is nothing wrong with using the Bosch CD box, unless you want to upgrade to a new part, as in the MSD 6. Then you could use the MSD coil. There are no performance advantages between the two CD boxes. I have tested this on the engine dyno. The MSD may work better for start up and low speed running. With proper spark plug heat range and carb. jetting, you should not have any problems with spark plug fouling with either box. You should stay with the OEM coil if you use the Bosch CD.