I ordered the MSD tach drive distributor and 6AL ignition box for my 71. Hopefully I will install it this weekend. I searched through some of the old threads and I'm somewhat confused on the installation.

Do all 71s have a resistor wire? What color is it? Do I need to remove it?

Looking at the instructions online, the only connection I'm uncertain of is the 12V switched red wire. If I use a multimeter and find a wire that is 12V with the key on and off when the key is off, then this will work for the red wire on the 6AL?

Also, anyone who has installed an ignition box, where did you put it? I'd rather not screw it into the firewall, any suggestions or pictures are welcome. Thanks.

 

Sonny:

I have this on my 72. I mounted it on the back side of the passenger side inner fender. It hides real nice. Did you get the blaster coil and the distributor? If so, pay attention on the distributor when you hook up the tach cable. There is a little adapter you'll need to put on the end of your tach cable and if you leave it off the tach will not work.

You'll need to pick up switched voltage to power the box!

You need to put between the box and this switched voltage a cut out switch. MSD won't tell you in the instructions but you don't want to charge the battery and you for sure don't want to use a jump box to start the car should the battery go down.

Trying to start the car with a battery charger hooked up is the kiss of death to a MSD box. The online instructions are pretty nice and just follow them to a T.

 

I replaced the resistor wire all the way back to the firewall junction - unwrapped the harness and pulled the wire out - bought the correct connector from O'Reilly and removed/inserted my replacement - sealed with silicone. From what I had read (through this forum) you don't want that resistor wire in-circuit with the coil. I also wired the positive to the starter motor and the negative to the frame. Works great and no issues at all.

Caveat: I had the motor out, so getting to the wiring harness and junction block was easy. Also, I have not had the motor over 4000rpm, this being a new build - some have reported that not running wires direct to battery can cause problems at higher RPM. 200 miles on the motor and it's strong - the MSD has not been an issue so far. I did what Willcox did - mounted the box on the passenger wheelwell behind the overflow tank and have the distributor and coil too. Very happy - nice and hidden and I can still get my hand in there to change the rev limiter resistor. I also wired the white wire to a kill switch and that works brilliant! So easy to do and some extra insurance to prevent theft.

S.

edit: 1970 big block.

 

Spinadog:

You are correct! The yellow wire that goes to the coil will have to be removed. On the MSD system you don't want the voltage to drop. If you use the yellow resistance wire it will!

Willcox

 

Thank you Sir!

That wire is easily identifiable from the spiral marking and sheath on it - looks like no other wire.

 

I previously purchased an MSD coil, can't remember which one, cannister style with a male plug connector, blaster 3? Is the adapter for the tach included with the distributor?

Haven't heard there may be issues if I don't go straight to the battery, I was planning on going to the starter solenoid, seems more convenient. Also, I'm not sure I have a yellow wire, my car is 200 miles away parked at my parents house where it basically died almost 6 weeks ago but I don't remember any yellow wires in my ignition. It may have already been removed. Looks like I'm going to have to try to figure out which wire/wires go to my ignition. Another post said there is an unused 12V source at the fuse box labeled IGN and to connect to that. I should probably invest in some alligator clips for my multimeter it sounds like I'm going to spend some time figuring out which wire goes where.

 

It has black speckles in it.

I said removed in my post above but it can also be taped back and a new wire run.

Depending on where you mount the box, the nearest switched voltage from the ignition switch will work.

Willcox

 

The adaptor is indeed included with the distributor.

 

There was a post about a year ago about the boxes blowing up. We called the tech support line since we were victims of blown boxes. The response we got was what I posted above. If you put a kill switch inline you won't have any problems with charging the battery.

You will have the yellow speckled wire. I did as you stated. . . I used the solenoid for my power supply. It's switched voltage and close the back of the inner fender and feeding a wire back to the fuse panel is a pain.

The box is sealed so don't worry about water getting on it. If you ever took one apart you would see all the internal parts are covered about an inch thick in a goop. Water can't get there even if you tried. I tried to fix one of our blown boxes and I did more damage trying to get to the electronics through this goop.

You'll be fine, just follow the instructions to a T.

Willcox

 

Yup, black speckles in a spiral pattern - should have clarified. Anyhoo, no other wire in that harness has that 'woven' look to the sheath...

edit: eh - may not be spiral, but the sheath is unique.

 

I have the same dist. and MSD 6al box it went up in smoke about a month ago. Was cruising for an hour at 65mph. When I exited the highway I noticed the car was idling higher than normal. About another 5 miles the car just died. I rolled into a parking lot and opened the hood and made a few checks then tried to start it. At that point a puff of smoke came out from the box I have mounted to the back of the driver fender skirt. The box was installed in 03 and given the amount of time actually used on the car is not that much. I was in a jam so I picked up another new box at Advanced auto. I sent my old box to MSD for repairs $55.00 so now I carry a spare box

 

I also have the same setup with 6AL box, blaster2 coil and tach drive distributor. In order to keep the engine compartment as clean as possible, the msd-box and coil is placed in passenger side under the dash board. Then its just connected to the distributor with one of those special firewall connectors. Works perfect for me...

 

Okay, I got my stuff yesterday. Willcox, the kill switch you are talking about is just a regular toggle switch wired on the small red wire? I just need to remember to flip this switch if I have to charge the battery?

 

 

U only need a resistor wire for the stock coil - buy a Blaster II for your MSD set up. U can bypass the resistor wire (or balist reisistor if u have that). Measure the wire resistance compared to regular size wire - resisto wire is several ohms per foot compared to less than 1 ohm per hundred feet on normal automotive wire.

Go to the MSD website for good instructions. I found i had to roll the wires from the MSD dist harness to the MSD 6AL box - meaning could not wire purpule to purpule wires. U need to verify this for yourself - becarful and double or even triple check this on the diagrams.

I can remember i ran the red coil wire from the MSD 6AL box but the box power came from a "Hot" terminal on the drivers fender.

U can mount the box anywhere but the cooler the better and using the rubber mounts will reduce vibration.

Good luck and hope this helps,
cardo0

 

Is this the resistance wire, vv

The wire is red, the sheath is off white/yellow. Only different wire I see, it's connected into the 3 wires that go to the unilite which also connects to the + on the coil.

Also, I just noticed the black wire that the sheathed wire is connected to is labeled 'resistance'

 

I traced the sheathed wire to the + terminal on the starter solenoid, resistance from the connector where the black and sheathed wires are connected to the + on the starter solenoid is only .3 ohm. So, the black wire must be the resistance wire and it should go back to my key right?

 

As Mr. Wilcox said you won't need the wire from the starter to the coil when using a MSD box. And u can bypass the resistor wire but u will need to identify the resistor wire - this can be done just like u are trying with the multimeter (good job). It should come from the firewall plug and on the other side of that plug is the wire that goes to the ign sw.
U should be able to power the coil with the output from the MSD box. Did u look at the MSD website? Once u run the coil wire from the MSD box i believe u can cut and tape back the old coil (resistor) wire - but please verify this on the MSD website.

Ok, i looked at the MSD w/s instructions for the 6AL and it says the 6AL "orange" wire goes to the coil positive (+). And the "black" wire from the 6AL goes the coil negative (-). The 6AL "red" wire needs to go to your ign sw and u will need to find this on a wiring diagram for your car. It should be the wire opposite the resistor wire to the coil and connects to the ign sw.
Chiltons has the cheapest books with the drawings next would be an exploded dwg from Zip or Ecklers. I hear Dr. Rebuild has some good dwgs but thats not a supporting vendor here.
Regardless Sonny u will need to find the correct wire out of the ignition sw and may need to ask an electrician for help reading the dwgs.

Now, i see u have "Unitlite" dist and that's made my Mallory. I don't have any experience with those but i would look on their w/s for instructions just like the MSD.

Hope this helps ya' and let us know if u have any specific questions,
cardo0