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Thread: Quick MSD question

  1. #1
    Some Kind Of Monster
    Is it ok to wire my 6al box to my wiring terminal block, or should I run it all the way to the battery?

  2. #2
    Jetaholic
    I'd take it straight to the battery. The red wire that goes to the ignition switch should go to the terminal block. That wire just carries an "On" signal to tell the box to turn on. But the two hardwired power wires should come straight off the battery for the best connection.

  3. #3
    Senior Member
    Join Date
    Feb 2009
    Posts
    2,626
    I would recommend NOT hardwiring to the battery. The better place to get your B+ connection would be the B+ terminal of starter solenoid(Ford or GM style). Gets it far from the battery and any potential corrosion. Keep your battery connections down to one positive cable and one negative cable.

  4. #4
    SmokinLowriderSS
    Go with Oldsquirt.

  5. #5
    Ryan00TJ
    I would recommend NOT hardwiring to the battery. The better place to get your B+ connection would be the B+ terminal of starter solenoid(Ford or GM style). Gets it far from the battery and any potential corrosion. Keep your battery connections down to one positive cable and one negative cable.
    That's the way I have mine. Works great and is as mentioned the cleanest and most efficient way.

  6. #6
    Some Kind Of Monster
    I would recommend NOT hardwiring to the battery. The better place to get your B+ connection would be the B+ terminal of starter solenoid(Ford or GM style). Gets it far from the battery and any potential corrosion. Keep your battery connections down to one positive cable and one negative cable.
    That's what I was thinking. It's much cleaner this way too. Doesn't the B+ (orange) wire go straight to the coil though? I have the digram right in front of me and that is what it says.

  7. #7
    HONDOG
    Taking your B+ and B- from remote locations is cleaner but be sure the B- is on the connection point for your negative battery cable.(Where it bolts to the block, no where else!) MSD's are VERY GROUND SENSITIVE! (I know, after loosing 2 from ground issues over the years) This is per MSD tech personnel.
    Bob

  8. #8
    cfm
    Another problem with going directly to battery is if you have multiple batteries. Seen this many times - master switch on #2 battery but ignition hardwired to #1. (Or vice versa) Doh!
    Speaking of battery switches, I've connected the positive from the ignition box to the 'out' connection of switch. Usually nice and dry in here and as close to battery(ies) themselves without dealing with the degassing green corrosive stuff. No taking wires off and on like usually happens on the battery.
    Point on ground above is very important.

  9. #9
    Jetaholic
    That's what I was thinking. It's much cleaner this way too. Doesn't the B+ (orange) wire go straight to the coil though? I have the digram right in front of me and that is what it says.
    Coil B+/B- and Box B+/B- are two different things. Box B+ should come from the battery side of the solenoid and Box B- should be grounded to the block as per Oldsquirt's instructions. THE ONLY TWO WIRES THAT WILL CONNECT TO THE COIL ARE THE ORANGE AND BLACK WIRES COMING FROM THE BOX!!! These wires carry Coil B+/B-.
    Basically what happens inside of an MSD box is box power comes in on the two hardwired black and red wires. These wires feed the amplifier circuitry in the box. However, they also feed a step up transformer that steps the voltage up from 12 volts to about 460-480 volts. This 460-480 volts charges up the discharge capacitor inside the box.
    When the mag pickup in the distributor sends a trigger signal to the box, it triggers the box to dump the charge from the discharge capacitor into the orange and black wires (coil B+/+-), and then into the coil's primary coil, which causes the magnetic field in the coil's primary to build and collapse. When this magnetic field builds and collapses, it induces a much higher voltage into the secondary side of the coil. And since it's a much stronger magnetic field than what 12 volts can provide, it induces a much higher voltage into the coil secondary than a 12 volt collapsing magnetic field can provide, which gives you the hotter spark.
    Basically think of the red and black wires as a B+/B- input while the orange and black wires are a B+/B- output, or source.
    The red wire on the weatherpak connector merely serves as a turn on signal wire that tells the box when to turn on and off. Think of this wire as the "remote" wire on a car amplifier...basically it does the same exact thing.

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