Ifitaintbroke Posted November 13, 2023 Share Posted November 13, 2023 Running into an issue installing my 6al. I ran all of the wires together, in one large harness, to the box. Box is mounted in the cab under the driver's seat. Then, I noticed in the instructions that the trigger wires are supposed to be run separately from any other wires. Called tech support and they said that the trigger wires should be at least 6 inches away from any other wire. Problem is there's no physically possible way to do that. My observations: if that's the case, then why do all the wires enter the MSD box at the same point? That doesn't make much sense. They're already touching each other AT THE BOX. Also, I'm using the white and red wires and a Pertronix module. Observation on that: the white wire is a trigger wire, meant to send a signal to the box. The red wire is not. If I understand correctly, it is simply a power wire. Obviously MSD intended them to be run together because they share a piece of shielding. So, why is it ok to run that power wire next to a trigger wire, but none others? I'm sure most of you on the forum have had cd boxes before. Is it really that big of a deal? Is it likely to cause a miss? Opinions please! Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 13, 2023 Share Posted November 13, 2023 I can't really speak to the Pertronix unit's wiring, but I can speak to the issue of running wires in parallel. The longer the wires run in parallel the more coupling there is between them. So the wires entering the box together doesn't really matter, it takes distance to effect coupling. But if you run the sensitive wires in a shield and ground one end of the shield then you can run them parallel to the other wires. Link to comment Share on other sites More sharing options...
Ifitaintbroke Posted November 14, 2023 Author Share Posted November 14, 2023 I can't really speak to the Pertronix unit's wiring, but I can speak to the issue of running wires in parallel. The longer the wires run in parallel the more coupling there is between them. So the wires entering the box together doesn't really matter, it takes distance to effect coupling. But if you run the sensitive wires in a shield and ground one end of the shield then you can run them parallel to the other wires. What kind of shielding are you referring to? It would have to be metal right? Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 14, 2023 Share Posted November 14, 2023 What kind of shielding are you referring to? It would have to be metal right? Yes, it would typically be metal. I used this stuff from Amazon on Big Blue. It is tinned copper and can be opened up for about any size of wire run. But running under the truck I'd put it in a piece of split loom to provide some protection. Link to comment Share on other sites More sharing options...
Ifitaintbroke Posted November 14, 2023 Author Share Posted November 14, 2023 Yes, it would typically be metal. I used this stuff from Amazon on Big Blue. It is tinned copper and can be opened up for about any size of wire run. But running under the truck I'd put it in a piece of split loom to provide some protection. Looks good! Guess I'll be trying that then. I'm assuming it should shield the trigger wire well enough to run it in a harness with the others? Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 14, 2023 Share Posted November 14, 2023 Looks good! Guess I'll be trying that then. I'm assuming it should shield the trigger wire well enough to run it in a harness with the others? Yes, it should. But a shield really shouldn't be grounded in more than one place. The reason for that is because no two places on a vehicle will be at exactly the same voltage. So if you ground it in two places you'll have a current in the shield and that will induce a signal onto the wires inside. It may not be much, but you aren't supposed to do it. Link to comment Share on other sites More sharing options...
Ifitaintbroke Posted November 14, 2023 Author Share Posted November 14, 2023 Yes, it should. But a shield really shouldn't be grounded in more than one place. The reason for that is because no two places on a vehicle will be at exactly the same voltage. So if you ground it in two places you'll have a current in the shield and that will induce a signal onto the wires inside. It may not be much, but you aren't supposed to do it. Thanks, Gary. I just ordered some. I thought I had gotten myself into a huge nightmare. I wonder though, do most people who put in an Msd box go through all this trouble? I doubt it. And that's probably why so many of them have issues. Link to comment Share on other sites More sharing options...
Gary Lewis Posted November 14, 2023 Share Posted November 14, 2023 Thanks, Gary. I just ordered some. I thought I had gotten myself into a huge nightmare. I wonder though, do most people who put in an Msd box go through all this trouble? I doubt it. And that's probably why so many of them have issues. I'm guessing that most people don't put the box under the seat, so their wiring is a lot shorter than yours. And it is the length, plus proximity, that does the coupling. Link to comment Share on other sites More sharing options...
Ifitaintbroke Posted November 14, 2023 Author Share Posted November 14, 2023 I'm guessing that most people don't put the box under the seat, so their wiring is a lot shorter than yours. And it is the length, plus proximity, that does the coupling. Touché. Link to comment Share on other sites More sharing options...
Ifitaintbroke Posted November 14, 2023 Author Share Posted November 14, 2023 I'm guessing that most people don't put the box under the seat, so their wiring is a lot shorter than yours. And it is the length, plus proximity, that does the coupling. Also, underwood heat and vibration cause problems with longevity. Hopefully I've eliminated that. Link to comment Share on other sites More sharing options...
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