MSD ignition setup and wiring question.
Thread Starter
Safety Car
Joined: Oct 2000
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From: Lake Wylie, South Carolina
MSD ignition setup and wiring question.
I got the box and coil mounted and I know where all the wires go the only problem is the 12 v ignition wire that is on the car. I swear my '71 wiring chart must be a mis print or this car has been seriously re wired. Only about half the wiring colors on the diagram match what is actually on the car. Below is a picture of what I am pretty sure is the origional 12v switched wire going to the positive side of the stock coil. I need to cut the old terminal off and attach the new terminal to the wire in order to hook it to the red lead from the MSD box.
What is the deal with the black wire attacthing to the same place and do I include it in the new connection? Sorry bout the blury pic. The camera battery died. You are looking at a red wire and a black wire connected to a "c" connector.
Also are there any wires that I disconnect now from the starter since I am using the msd setup?
Thanks
Wade
What is the deal with the black wire attacthing to the same place and do I include it in the new connection? Sorry bout the blury pic. The camera battery died. You are looking at a red wire and a black wire connected to a "c" connector.
Also are there any wires that I disconnect now from the starter since I am using the msd setup?
Thanks
Wade
Melting Slicks
Joined: Dec 2004
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From: Cruising somewhere in St. Louis, Missouri
the only two wires attaching to the coil come from the Box...I they are the orange and black wires that are wrapped together. There should be a 12v wire that came from the + side of the coil that attaches to the red single wire to the box.
you may need to put a meter on the wires to see which one is the 12v ignition wire that gets power from turning the key.
your missing one picture in your post so can't see what your talking about but in other the blurry picture I assume these came from the coil so the red wire attaches to the red going to the coil and the black wire from the coil attached to the white wire from the coil.
you may need to put a meter on the wires to see which one is the 12v ignition wire that gets power from turning the key.
your missing one picture in your post so can't see what your talking about but in other the blurry picture I assume these came from the coil so the red wire attaches to the red going to the coil and the black wire from the coil attached to the white wire from the coil.
Last edited by luerja; May 14, 2006 at 01:48 PM.
Thread Starter
Safety Car
Joined: Oct 2000
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From: Lake Wylie, South Carolina
luerja,
Thanks for the reply. I have all of the wires right for the msd box, coil and distributor. The problem I am having is ID'ing the 12v wire in the cars engine harness. I know it is the one in the pic problem is it does not match color wise with my chart and it also has a black wire combined to it. I need to know is this the correct engine harness wire to hook the red lead from the box to? Also I fixed the pic.
Thanks again
Wade
Thanks for the reply. I have all of the wires right for the msd box, coil and distributor. The problem I am having is ID'ing the 12v wire in the cars engine harness. I know it is the one in the pic problem is it does not match color wise with my chart and it also has a black wire combined to it. I need to know is this the correct engine harness wire to hook the red lead from the box to? Also I fixed the pic.
Thanks again
Wade
Thread Starter
Safety Car
Joined: Oct 2000
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From: Lake Wylie, South Carolina
K maybe this will help? Keno are you saying that you connected both the heavy red and the switched red to the starter?
Thanks guys!
Thanks guys!
Last edited by ImBatman; May 14, 2006 at 06:34 PM.
Melting Slicks
Joined: Nov 2004
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From: Pineville Kentucky
CI 6-8-9 Veteran
I hooked my "small" red wire together to the existing wires that were on the stock coil and the "heavy" (power) red wire to a 12v junction mounted on the fenderwell and the ground on the alternator ground. Worked like a top!
Thread Starter
Safety Car
Joined: Oct 2000
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From: Lake Wylie, South Carolina
Originally Posted by wnjlt1
wade, do you have a test light or volt meter?
2th farmer - it has been so long since a running motor was in the car that I cannot rember the wire location and the wire that I have pictured in the origional post is the one that I am pretty sure is the 12v switched that went to the coil. Problem is the color does not match the one on the wiring diagram or in in the AIM. It also does not mention the black wire tht is combined with the red one I am holding in the pic. Again I am pretty sure that I have the right wire to put the connector on to hook to the small red lead from the box. Again just not sure about that combined black wire.
Thanks
Wade
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Joined: Jan 2005
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From: Tucson Arizona
I think 
on my '71 there was a wire from the starter that went to the positive side of the coil. This wire was on the other small post on the starter not the bat or the post to energize the starter. The theory was to provide extra power to the coil while cranking. I left it out when I installed my first MSD years ago.
on my '71 there was a wire from the starter that went to the positive side of the coil. This wire was on the other small post on the starter not the bat or the post to energize the starter. The theory was to provide extra power to the coil while cranking. I left it out when I installed my first MSD years ago.
Melting Slicks
Joined: Nov 2003
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From: St. Charles Mo
CI 5 & 8 Veteran
Originally Posted by BlackRat
K maybe this will help? Keno are you saying that you connected both the heavy red and the switched red to the starter?
Thanks guys!
Thanks guys!
Wade, the red wire (jacketed by a white nylon shield cloth) in your first pic looks like the wire that attaches to your positive terminal of the coil. That wire has a resistance built into it to lower the votage to the coil. The correct wire that should be connected to the red MSD wire is back prior to that resistive red section of wire. I think ignition 12v is represented by a pink wire usually located back under the dash in the wire harness. Don't use the red resistive wire, it will result in lowering the voltage when current is drawn by the MSD.
It is best to attach MSD supply power direct to the battery as indicated in the schematic, when posible. The computer chip electronics in the MSD require a clean power supply with no noise or voltage spikes. Yes there is power regulating circuits internal to the MSD and you can get lucky by attaching some other location, but battery is best, offering the cleanest power.
Bullshark
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From: Smile, it's just the internet.
Unorthodox, but I went to the hardware and bought a 10' length of 10-2 burial-rated stranded (for flexibility) cable. I hooked it to the side terminals on my battery and snaked it under the car, alongside the factory positive, and up the firewall directly to the MSD.
I don't remember where I pulled the switched hot from. Best bet would be to borrow a battery from another car for an hour or two and put a meter on your wires to ID what you need.
I'm pretty sure I have only three wires to the starter. Seems like I had to eliminate one. I have the heavy cable directly from the batt., a ground (to the frame?), and the wire from the "start" terminal on the ignition switch (should only be hot while cranking).
Not sure if that helps or not. I did this exercise two years ago and I don't remember...
I don't remember where I pulled the switched hot from. Best bet would be to borrow a battery from another car for an hour or two and put a meter on your wires to ID what you need.
I'm pretty sure I have only three wires to the starter. Seems like I had to eliminate one. I have the heavy cable directly from the batt., a ground (to the frame?), and the wire from the "start" terminal on the ignition switch (should only be hot while cranking).
Not sure if that helps or not. I did this exercise two years ago and I don't remember...
Thread Starter
Safety Car
Joined: Oct 2000
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From: Lake Wylie, South Carolina
Originally Posted by Bullshark
Wade, the red wire (jacketed by a white nylon shield cloth) in your first pic looks like the wire that attaches to your positive terminal of the coil. That wire has a resistance built into it to lower the votage to the coil. The correct wire that should be connected to the red MSD wire is back prior to that resistive red section of wire. I think ignition 12v is represented by a pink wire usually located back under the dash in the wire harness. Don't use the red resistive wire, it will result in lowering the voltage when current is drawn by the MSD.
It is best to attach MSD supply power direct to the battery as indicated in the schematic, when posible. The computer chip electronics in the MSD require a clean power supply with no noise or voltage spikes. Yes there is power regulating circuits internal to the MSD and you can get lucky by attaching some other location, but battery is best, offering the cleanest power.
Bullshark
It is best to attach MSD supply power direct to the battery as indicated in the schematic, when posible. The computer chip electronics in the MSD require a clean power supply with no noise or voltage spikes. Yes there is power regulating circuits internal to the MSD and you can get lucky by attaching some other location, but battery is best, offering the cleanest power.
Bullshark
Thanks Bullshark I will peel back the tape tonight to the point that I see the coreect wire and then double check with a volt meter. The continuos power supply to the msd box can be connected to the positive post on the starter couldn't it? This would be the same as connecting directly to the battery since the positive cable connects to the starter.
Hopefully last question. I need to install the purple wire in the car harnes to the inboard "S" terminal of the starter correct? Since I have the orange and black wires running from the MSD box to the + and - sides of the coil do I still run a wire from the outboard terminal on the starter opposite the "S" terminal back up to the coil?
Thanks
Wade
Melting Slicks
Joined: Nov 2003
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From: St. Charles Mo
CI 5 & 8 Veteran
Originally Posted by BlackRat
Thanks Bullshark I will peel back the tape tonight to the point that I see the coreect wire and then double check with a volt meter. The continuos power supply to the msd box can be connected to the positive post on the starter couldn't it? This would be the same as connecting directly to the battery since the positive cable connects to the starter.
Hopefully last question. I need to install the purple wire in the car harnes to the inboard "S" terminal of the starter correct? Since I have the orange and black wires running from the MSD box to the + and - sides of the coil do I still run a wire from the outboard terminal on the starter opposite the "S" terminal back up to the coil?
Thanks
Wade
Hopefully last question. I need to install the purple wire in the car harnes to the inboard "S" terminal of the starter correct? Since I have the orange and black wires running from the MSD box to the + and - sides of the coil do I still run a wire from the outboard terminal on the starter opposite the "S" terminal back up to the coil?
Thanks
Wade
Yes, there needs to be a switched +12v starter wire to the solenoid S terminal to activate the starter....I do believe it is a purple wire coming from the ignition (starter) switch if my memory is any good
Since it looks like you are planning a magnetic pickup distributor setup, you have elliminated the ballist resistor and have no points to protect, you don't need a wire from the (I) terminal on the solenoid to the + terminal of the coil. I know I told you to eliminate the ballist resistor, but I am betting that there is very low current associated with that wire so, it probably dosn't matter if you remove it or not. As I remember, the red ballist resistor wire runs back toward the ignition switch and then connects to another wire via a small connector. That is the point I used. I will try to post a basic wiring diagram of our old setup which might make this all a little more clear.
Bullshark
Last edited by Bullshark; May 15, 2006 at 04:34 PM.
Instructor
Joined: Aug 2005
Posts: 209
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From: Hollywood FL
Just one comment on your install, Wade. You might want to find a place where the MSD won't be exposed to high underhood tempertures. I mounted one like that in my car and less than 2 years later it started giving me problems. I sent it to MSD for repair and they said it was heat damaged. I relocated it inside the car and never had another problem. I mounted mine on the passenger side under the dash on the backside of the map pocket panel. I've also seen them put in the parking brake console. It might save you a headache down the road. Just my .02
Doug
Doug
Melting Slicks
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For a switched connection, you can use the original wire with the ballast resistor/wire disconnected. Or you can tap into one of the 2 small wires at the alternator, if it's a 4 wire. One is a sensor wire, and always hot. The other is the excitation wire that is keyed to the ignition, no resistor wire.
Thread Starter
Safety Car
Joined: Oct 2000
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From: Lake Wylie, South Carolina
Thanks guys I think that this clears up a lot. I am going to go and buy a new battery tomorrow and trace down the 12v switched wire that is attached to the one I have pictured.
Doug,
After looking at everything I think I probably will move the ignition box behind the passenger dash panel. The harness that came with the box is so long I don't want to run the risk of melting the wires as well as heat soaking the box.
Thanks again guys I will keep you updated.
Wade
Doug,
After looking at everything I think I probably will move the ignition box behind the passenger dash panel. The harness that came with the box is so long I don't want to run the risk of melting the wires as well as heat soaking the box.
Thanks again guys I will keep you updated.
Wade
Thread Starter
Safety Car
Joined: Oct 2000
Posts: 4,282
Likes: 172
From: Lake Wylie, South Carolina
Thanks guys I think that this clears up a lot. I am going to go and buy a new battery tomorrow and trace down the 12v switched wire that is attached to the one I have pictured.
Doug,
After looking at everything I think I probably will move the ignition box behind the passenger dash panel. The harness that came with the box is so long I don't want to run the risk of melting the wires as well as heat soaking the box.
Thanks again guys I will keep you updated.
Wade
Doug,
After looking at everything I think I probably will move the ignition box behind the passenger dash panel. The harness that came with the box is so long I don't want to run the risk of melting the wires as well as heat soaking the box.
Thanks again guys I will keep you updated.
Wade
Melting Slicks
Joined: Nov 2003
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From: St. Charles Mo
CI 5 & 8 Veteran
Here is a simplified basic schematic of the Delco system, similar to our corvette setup. As you can see, the ballast resistor is bypassed when the starter is cranking the engine. The ballast resistor's purpose is to limit the current thru the points during normal operation so, with the MSD setup (ballast resistor removed), the wire from the (I) terminal of the solenoid is not needed.
Bullshark
Bullshark
