'68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness - Team Camaro Tech
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post #1 of 12 (permalink) Old Dec 21st, 09, 04:45 PM Thread Starter
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Brian
 
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'68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness

Alright guys, I think I've compiled together all the information into one place, I'd appreciate it if someone double-checked my work.

This is a new install of a 468-big block into a '68 RS with console gauges, tic-toc-tach. Upgraded with a full MSD ignition system, also updated to a SI-series alternator. The attached diagram is what I think are the wiring changes/hook-ups needed to make it all work, gathered from various sources.

Here's the summary of what I have:
  • MSD 6AL
  • MSD 85551 Pro Billet Distributor
  • MSD Blaster 2 Coil
  • MSD Tach Adapter
  • Factory Tic Toc Tach
  • GM SI-Series (internal regulated) Alternator
  • Stock '68 Engine Wiring Harness
  • Edelbrock Carb w/ Electric choke

If this is right, I might just be the hero of the internets (or at least this forum )

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post #2 of 12 (permalink) Old Dec 21st, 09, 08:10 PM
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Rod
 
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Re: '68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness

that diagram is a total saver, your going to answer a lot of questions

Rodney

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post #3 of 12 (permalink) Old Dec 23rd, 09, 07:38 AM
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John Fivian
 
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Re: '68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness

First off, awesome picture.
I'm having a problem with my MSD 6AL right now I think. I have my small red wire T'd into the pink wire, so the 6AL only gets power in the ON and START position, not in the accessory position. According to your picture, you have your small red wire connected to the choke - but where do you have the choke connected to to get its power? Sorry, I know I'm not helping you, but your picture is timely and very handy with regard to my problem.

John Fivian
68 327
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post #4 of 12 (permalink) Old Dec 23rd, 09, 08:50 AM
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Re: '68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness

awesome, just saved the pic too!

Armando

1967 Chevy Camaro RS/SS
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2007 Ford Mustang GT/CS (sold)
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post #5 of 12 (permalink) Old Dec 23rd, 09, 09:15 AM Thread Starter
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Brian
 
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Re: '68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness

Quote:
Originally Posted by JHunter View Post
First off, awesome picture.
I'm having a problem with my MSD 6AL right now I think. I have my small red wire T'd into the pink wire, so the 6AL only gets power in the ON and START position, not in the accessory position. According to your picture, you have your small red wire connected to the choke - but where do you have the choke connected to to get its power? Sorry, I know I'm not helping you, but your picture is timely and very handy with regard to my problem.
Hey Hunter, that schematic isn't a literal wiring diagram--just how it should flow. Your choke should be hooked up to a 12V switched power source (i.e. turns on with the key).

In my case, the MSD, Tach Adapter, and choke were all in the same vicinity, so I hooked them all up to the same wire coming from the harness. Since I bypassed the resistor wire, it's providing the full 12V needed.
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post #6 of 12 (permalink) Old Dec 23rd, 09, 03:32 PM
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Steve
 
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Re: '68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness

Page 138 of the MSD 2010 catalog says..

"GM TACHOMETER
GM vehicles have an in-line filter that should be bypassed if the
factory tachometer drops back to zero as the engine rpm increases.

The drawings below show what the filter might look like. For correct
operation, disconnect both wires from the filter and leave them
disconnected. Connect the wire going to the tachometer to the MSD
Ignition unit tach output terminal
"

It diesn't suggest to use a tach adaptor for GM tachs on the following page either..

Have you found that the tach adaptor (assuming a model 8920) has cured your tach problems, and what exactly were they?

Nov 68 Van Nuys. 327 floor-shift-auto, Frost Green and not much else when new.

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post #7 of 12 (permalink) Old Dec 24th, 09, 06:07 AM
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Steve
 
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Re: '68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness

Hey, on a 68, what happens to the 20 W/B & PPL wire to the positive coil when it heads through the bulkhead connector? Does it come out as the 12R? If so, then where does the 18BRN go?
On UPC12-D2, it seams to completely disappear. Nine wires in on the engine side, only eight out on the dash side.. What gives?

Also, great diagram, and if I may offer a small suggestion..
To clean the install a tad, ground the MSD at the fender 12B ground screw and power it at the junction block. This will also take advantage of the 14R which is a fusable link. Those two points readily accept ring terminals which will keep your battery terminals clear and the wiring can easily be hidden and out of the way.

Nov 68 Van Nuys. 327 floor-shift-auto, Frost Green and not much else when new.

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post #8 of 12 (permalink) Old Dec 30th, 09, 03:11 PM Thread Starter
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Brian
 
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Re: '68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness

Quote:
Originally Posted by BlackoutSteve View Post
Hey, on a 68, what happens to the 20 W/B & PPL wire to the positive coil when it heads through the bulkhead connector? Does it come out as the 12R? If so, then where does the 18BRN go?
On UPC12-D2, it seams to completely disappear. Nine wires in on the engine side, only eight out on the dash side.. What gives?

Also, great diagram, and if I may offer a small suggestion..
To clean the install a tad, ground the MSD at the fender 12B ground screw and power it at the junction block. This will also take advantage of the 14R which is a fusable link. Those two points readily accept ring terminals which will keep your battery terminals clear and the wiring can easily be hidden and out of the way.
Hey Steve.. that is the "resistor wire" as well as a length of wire that doesn't go back to the harness, it drops out to the starter location. On my harness, the "ppl" wire was actually yellow. For my needs, I just removed both from the harness completely... also the tach wire happened to be missing on my engine harness, but existed on the dash-side one. You might have the exact opposite, which could explain why you have more wires on the engine side versus the dash. I ended up running a new wire through the junction block and into the car by splicing on a spade connector and just shoving it in there

Great idea on the grounding/power. I grounded the MSD at the screw on the fender like you mentioned, but went a little "fancy" and mounted up a 4-terminal junction block for 12V power from the ignition. That way I have the MSD, the choke, the and the tach adapter all nicely tied up in one spot. I'll have to get some pictures up here eventually
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post #9 of 12 (permalink) Old Jan 4th, 10, 12:12 PM
Craig
 
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Re: '68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness

Brainiator, thanks for the graphic. this is helpful as I am currently installing a 6AL-2 and MSD comparable distributor with magnetic pickup on my 68 with Tic Toc Tach. I have a few questions for you.
1. Did you have a ballast resistor before installing this box & distributor? I ask I have two different wires (pink, which connects to the resistor) and yellow which connected directly to the positive side of the coil and back feeds to the other end of the ballast resistor. I know the resistor has to be removed, so I think both the pink and the yellow wires will connect to the red wire from the 6AL-2 box. Both of these wires have battery voltage with the ignition on, but 0V with the ignition off.

2. What did the blue wire on your diagram replace? I'm wondering if this is my pink wire mentioned in #1 above.

3. The brown wire (originally the negative side of the coil) is now connecting to a pink wire on the tach adapter (#8920). Is this your tach signal?
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post #10 of 12 (permalink) Old Jan 6th, 10, 09:37 AM Thread Starter
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Brian
 
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Re: '68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness

Hi Craig, answers are inline below...

Quote:
Originally Posted by need2speed View Post
1. Did you have a ballast resistor before installing this box & distributor? I ask I have two different wires (pink, which connects to the resistor) and yellow which connected directly to the positive side of the coil and back feeds to the other end of the ballast resistor. I know the resistor has to be removed, so I think both the pink and the yellow wires will connect to the red wire from the 6AL-2 box. Both of these wires have battery voltage with the ignition on, but 0V with the ignition off.
Unfortunately, this is for a brand-new install. I started with a repro engine harness, and a completely redone motor with new components. From what I've found the coloring differs all over the place from the original GM schematic...what is a little scary is the yellow wire, I've heard if you leave that connected you can get some back-feed voltage and pop your MSD.

From the sounds of it, I'd actually just go the super simple route (this is what I ended up doing) and know that it'll work "for sure".

Under your dash, the fuse box will have a terminal labeled "IGN". Just run to the hardware store, pick up a female spade end, crimp it on, and run an 18G wire from there to your MSD. It's straight 12V, without the resistor sneaking in there. You could run it through the firewall at the fuse box mating point, or through something like the oil pressure sender hole (where I did). Much simpler, and it's really not a whole lot of work. A little bit of electrical tape, and you can even wrap it in the existing harness to make it look clean and factory.

Quote:
Originally Posted by need2speed View Post
2. What did the blue wire on your diagram replace? I'm wondering if this is my pink wire mentioned in #1 above.
I think it is. In my harness this was the fabric-wrapped resistor wire (white/blue) that also had that yellow jumper to the starter. As I mentioned above, I just chopped the ends off, wrapped it into the loom, and ran a brand-new 18G from the IGN term to a terminal I installed on the firewall.

Quote:
Originally Posted by need2speed View Post
3. The brown wire (originally the negative side of the coil) is now connecting to a pink wire on the tach adapter (#8920). Is this your tach signal?
Yes it is. That one was a new run--my engine-side harness never had it, but the under-dash one did.
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post #11 of 12 (permalink) Old Jan 6th, 10, 11:53 AM
Craig
 
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Re: '68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness

Thanks Brian. I appreciate the feedback. I restored my car and used replacement harnesses. Unfortunately, many of the wires differ in color from the original wiring diagrams for 68 and sometimes even change colors at the firewall. MSD tech told me to connect both the pink and the yellow to the red wire on the AL box, but my gut is telling me not to.
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post #12 of 12 (permalink) Old Jan 8th, 10, 10:15 AM Thread Starter
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Brian
 
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Re: '68 Camaro-> MSD / Tic Toc Tach / Alt Wiring w/Stock Harness

Quote:
Originally Posted by need2speed View Post
Thanks Brian. I appreciate the feedback. I restored my car and used replacement harnesses. Unfortunately, many of the wires differ in color from the original wiring diagrams for 68 and sometimes even change colors at the firewall. MSD tech told me to connect both the pink and the yellow to the red wire on the AL box, but my gut is telling me not to.
Yea, I definitely wouldn't do it. I think much of it depends on the type of starter you're using, but just "be sure" and take little extra time to do it the way where there is no doubt (from the fuse box) It's a lot less expensive than a new 6AL
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