1980 Porsche 911SC distributor connection
1980 911 SC - The magnetic pickup harness which extends from the MSD ignition module connects to the distributor. Do you cut and splice the green wire which clips into the distributor? Do you adapt the harness fitting to go to the old plug from the stock ignition model which now houses the ignition (red) and the tach (black/purple) connection? The instructions simply state the wires go to the magnetic pickup. Also the battery hot wire which connects to the starter - what is the best way to route the wire since the MSD module is mounted on the left side and the starter on the right side. Routing the wire over the transmission and through the oxygen sensor hole may find the hot wire and transmission linkage conflicting. Thanks for any help.
1978 911 SC from Australia
I own a 1978 911 SC and I’ve recently install an MSD 6Al ignition complete with a blaster coil and MSD Super Conductor ignition wires.
The biggest problem I had was working out the polarity of the magnetic signal from the Bosche distributor.
Please read the MSD bulletin on this subject. “tb_magnetic_trigger.pdf”
I wouldn’t modify the green wire going into the distributor. I modified the cable that was originally connected to the Bosche CD box so that it would plug directly into the magnetic trigger on the MSD ignition. The other end I left as is and plugged it directly into the Green wire from the Distributor.
I have included some pictures of my install just in case they help.
Peter K, You've done a beautiful job on engine compartment.
From the magnetic output wire on the 6AL, I should use the short adapter that comes with the unit and plug into the wiring harness once used by the old bosch unit. The green and purple wires on the MSD supplied adapter plug into what color wires on the old module plug. I currently have red into ignition and tach wire into black/purple. Thanks
Please see attached photos to this post.
It’s of my Bosche plug for the original CD unit of my car. I have removed the plug completely for my install but this isn’t necessary and probably wise not to if you want to keep your car as original as possible.
Please note: The wiring I have in this picture is how my car is currently wired. My car is a 1978 model and yours could be different. I’m guessing they are the same but considering the value of these old Porsches it pays to be extra cautious.
Please also note: From the picture that the stock Bosche CD unit has a ground going from the “Coil Negative” to the engine. (Near the earth for the spark plug wires) I would isolate this so that the “MSD Coil Negative” (black wire) does not go to ground.
I can not emphasise enough to make sure the polarity of the magnetic pickup from the Bosche distributor goes to the correct MSD MAGNETIC trigger wires…
If you have a timing problem or back firing while idling after completing the install: Check the polarity of the magnetic pickup wires of the distributor. Reverse the connectors and check the timing again. The correct polarity is whichever connection gives the most retarded timing.
MSD 6AL & Tach Adapter Install Guuide Porsche 911 SC
MSD 6AL Installation Guide for Porsche 911 SC
* Download the Document for Pictures & Diagrams *
You will need 2 MSD supplied parts to convert your 911 SC ignition from the Bosch or Perma-Tune Capacitor Discharge Ignition (CDI) system currently installed in your car. The first is a MSD 6AL or 6A. The 6AL is part number 6420 and has a rev limiter along with a few other benefits for not much more money. You will also need a MSD Tachometer Adapter part number 8920 for magnetic pickup distributors, like the one in the Porsche 911 SC. You need the tachometer adapter because the MSD 6AL can fire multiple times below 3000 RPM. The tachometer adapter assists the tachometer to accurately read the signals from the MSD 6AL.
Mounting the MSD 6AL ignition Unit: The hardest part of this project is getting the 6AL unit mounted where the old CDI unit was located before. The MSD 6AL is about double the size of the Bosch or Perma-Tune unit, making it necessary to redesign the mounting points on the aluminum install panel. In my 1979 911 SC I had to relocate my external alternator voltage regulator in order to fit the MSD 6AL on to the aluminum install panel. If your alternator has an internal regulator than you will obviously not need to do this. In some cars, you may have to relocate the rear window heater relay. Before you mount the 6AL unit, you will need to select the quantity of cylinders you wish the MSD unit to fire. Locate a knurled cap on the side of the unit, it will be held on by a single center mounted screw. Remove the cap and cut the red wire loop to select 6-cylinder operation. Replace the cap. However, before cutting, check the MSD install guide, supplied with the unit, to make sure that the wire colors have not changed on your MSD 6AL unit.
Wiring: Before you start removing old parts or doing any wiring, it is always a good idea to disconnect the battery. You can source about half of the connections required for installing the MSD 6AL ignition from the CDI plug that was used to supply connectivity to your Bosch or Perma-Tune CDI unit. Enclosed below is an overview of the connections on the CDI plug so that you can find where to connect the wires from the MSD unit to the CDI plug. Both my Euro 911 SC Coupe and my 911 SC Cabriolet had the same wire layout in the CDI plug. However, yours could be different, so pull back the rubber boot on the CDI plug and verify that your connections match the ones in the diagrams. All of the wire connections required to install the MSD 6AL and Tachometer Adapter are detailed later in this document.
Tools Required: Wire ties, drill (to install 6AL to aluminum panel), spade connectors (for plugging in wires to the CDI plug), wire stripers/cutters, metric socket set with wrench, Phillips head screw drivers, and floor jack or lift (for access under the car to attach the constant hot to the starter).
Before You Start the Car After Installation: Make sure you do not have solid core ignition wires. If so replace them. Check spark plug gap. “Experts” range in thought here, from leave it stock to widen the gap to .055. The truth lies somewhere in between. Check to make sure your coil is compatible with the MSD ignition from the list supplied with the new ignition unit. Once running, check the timing.
Good luck, I hope this install guide helps answer some questions you may have.
- Chris Champeau
Brown = System Ground
Black (Thin Wire) = Tachometer Signal
Black (Thick Wire)= Signal Ground from Distributor
Green = Trigger Signal from Distributor
Red = Power (Key Activated)
White = Coil Positive Connection
* Peel Back Rubber Boot to Verify Wire Colors
(I Could Not Post Pictures and Diagrams)
6-Pin CDI Connectors on the CDI Unit
31/1 TD 31d
Brown Thin Black Thick Black
A 15 7
White Red Green
31/1 (Brown) = Power Ground
(Not Used with MSD 6AL Unit)
TD (Thin Black) = Tachometer Signal
(Tach Output Wire from MSD 6AL Connects Here on CDI Plug)
31d (Thick Black) = Signal Ground for Trigger Signal
(Purple Wire from MSD 6AL Connects Here on CDI Plug)
A (White) = 460 Volt Coil Connection
(Not Used with MSD 6AL Unit)
15 (Red) = Power (Key Activated)
(Thin Red Wire from MSD 6AL Connects Here on CDI Plug)
7 (Green) = Trigger Signal from Distributor
(Green Wire from MSD 6AL Connects Here on CDI Plug)
MSD 6AL Ignition Part# 6420 Installation Wiring Guide
(For Magnetic Pickup Distributor On 911 SC Porsches)
Heavy Red Wire = Connect to the Hot Wire on Starter (Under Rubber Boot)
Heavy Black Wire = Connect to Ground
Thin Red Wire = Connect to 15 (Red Wire) in CDI Plug
Thin Black Wire = Connect to Negative Side of Coil
Orange Wire = Connect to Positive Side of the Coil
Purple Wire = Connect to 31d (Thick Black Wire) in CDI Plug
Green Wire = Connects to 7 (Green Wire) in CDI Plug
White Wire = Not Used with Magnetic Pickup Distributor on 911 SC
* Note: If Using Points Connect the White Wire to Distributor Wire
Do Not Use the Purple and Green Wires
MSD Tachometer Adapter Part# 8920 Wiring Guide
(For Magnetic Pickup Distributor On 911 SC Porsches)
Red Wire = Connect to Switched Positive (Red Wire on the CDI Plug)
Black Wire = Connect to Ground
White Wire = Connect to Tachometer Output on the MSD 6AL Unit
Purple Wire = Connect to Tachometer Input (Black Thin Wire on CDI Plug)
* Note: If Using Points Use MSD Tachometer Adapter Part# 8910
I have all the pictures if you need them, but I could not post them on this website.