MSD SCI/6a Installation (How-To)

UPDATE: I changed to a CS-144 Alternator and the "stay-on" problem is gone!

Disclaimer:

Perform these tasks at your own risk. I am not responsible for damages if either you screw up or if my text is faulty. Proceed at your own risk.

How-To:
1. Remove old coil.
If you have a strong enough coil you probably don't need to replace this. (The AC Delco stuff will burn out from what i've read.) Remove the coil bracket and the positive and negative leads connected to the coil and also remove the ignition source lead. You may want to take note of which wires are what. Stock GM usually use brown colored wire for ignition source. If you really want to be safe, disconnect the positive source from the battery - i found it unnecessary for this job if you're careful. If you're clumsy - DO IT.

2. Find a location for the MSD SCI/6a/6al unit. I chose the firewall right above the heater core. I struggled to find where I want to mount this. I hate making unnecessary holes in cars and I wanted to hide the unit for security. I couldn't put it inside the cab because those things are noisy and that would just drive me nuts. I can already hear the unit outside as it is. The noise sounds like a poorly installed sound system suffering from "engine noise" whine. I’m not using the heater so I wasn’t concerned about piercing the heater core. I’m going to replace it with a Vintage Air or Classic Air unit. I may need to remount the MSD then.

Anyway, make sure wherever you mount it you have enough clearance around the unit and around the coil. If you choose to mount the unit on the firewall make sure the MSD clears when the hood is shut. Also make sure you don't pierce anything important (behind the firewall in my case) with the mounting screws.

3. Testing

Since I bought everything used, I wanted to test it before I started mounting and drilling. This is a good precaution prior to routing wires too. I had initially thought I had a magnetic pickup distributor. After further inspection, I found out I had an MSD distributor. I was as surprised as anyone. In any event, the wiring was pretty straight forward if you follow the 2^nd diagram on page 11 of the manual (http://www.msdignition.com/pdf/6%20series/6series.pdf). Should be straight forward but remember to bridge the smaller 16 gauge red wire coming out of the distributor with the red wire out of the MSD to the ignition. Both red wires from the MSD and the Distributor need Ignition (+) input. The orange wire from the distributor connects to the white wire on the MSD. The black and red pair coming out of the MSD connects to the (+) positive and (-) negative poles from the coil.

4. Final Wiring and Mounting

I was concerned about the effects of high vibration on the MSD and the coil. This is probably overboard but I decided to cut out a rubber backing that goes in between the firewall and the MSD/Blaster Coil. It worked out very well.

After installing and mounting the MSD and Coil cut the wires to length and solder together. Soldering is the best connection you can do. I personally can’t stand seeing butt-connectors or quick connects. Buy some heat shrink or use 3M black tape to wrap up the exposed wire. To be certain wrap the taped area with a zip tie/cable tie to ensure the sucker stays covered.

I had the “run-on” problem I read about earlier. A diode to the alternator fixed that right up. You can see the picture below. I will redo this portion of the install because I mistakenly connected the diode to the return line of the alternator rendering my voltage meter in the cabin inactive. If you have this problem, see below notes.

MSD SCI Product Review:

I have yet to tune my Edelbrock Carburetor but so far the biggest difference in my setup was the coil. I tested 1) without the MSD SCI but with the coil and 2) with both. Not much difference with both. It's noticeable, yes, but could I have lived without the ignition unit? Yes, probably. It does idle smoother somewhat (again, I believe I have a lot to gain from just tuning my carb) but no real big differences otherwise. It starts just as quickly with or without the MSD. It was poor starting with the old coil however so i'm a happy camper :). I read the reviews online about the MSD SCI/6a/6al and I honestly think some of those guys suffer from sense of dillusion. In theory, multiple sparks, for one power stroke should yield better combustion - and it probably does, but I have yet to notice a groundshaking difference. Hopefully once I tune my carb or perhaps if I toss it on a dyno the difference will be more apparent. I'm sure the unit yields more noticeable results from a built N/A motor or in a forced induction situation.

Parts:

1. MSD SCI (Sport Compact Ignition) - $80

2. MSD Blaster SS Coil - $25

Purchase Location:

1. Craigslist

Documentation:
1. MSD 6A/6AL installation instructions from MSD
2. MSD SCI installation instructions from MSD

Had the engine run-on problem described on page 8 of the 1st pdf manual.

"ENGINE RUN-ON
If your engine continues to run even when the ignition is turned Off you are experiencing engine Run-On. This usually only occurs on older vehicles with an external voltage regulator. Because the MSD receives power directly from the battery, it does not require much current to keep the unit energized. If you are experiencing run-on, it is due to a small amount of voltage going through the charging lamp indicator and feeding the small Red wire even if the key is turned off.

Early Ford and GM: To solve the Run-On problem, a Diode is supplied with the MSD in the parts bag. By installing this Diode in-line of the wire that goes to the Charging indicator, the voltage is kept from entering the MSD. Figure 6 shows the proper installation for early Ford and GM vehicles.

Note:Diodes are used to allow voltage to flow only one way. Make sure the Diode is installed facing the proper direction (as shown in Figure 6).

Ford: Install the Diode inline to the wire going to the #1 terminal.

GM: Install the Diode in-line to the wire going to terminal #4."