install msd

[gaddy 69]

hi im installing a msd 6al in my 70 challenger and need a switched hot wire can i use the old + side coil wire

 

[70chall440]

Brown and blue wires going to the ballast resistor

 

[gaddy 69]

Brown and blue wires going to the ballast resistor

yes i see the two wires brown and blue but which one can i use

 

[70chall440]

Sorry, my bad I was thinking about an EFI system. Are you trying to connect the red MSD wire? What distributor are you using. Perhaps this diagram will help; the red wire connects to the blue wire running to the BR

 

[72RoadRunnerGTX]

yes i see the two wires brown and blue but which one can i use

The blue (ign 1,+12v ignition run only) wire and the brown (resistor by-pass, +12v cranking only) wire have to be connected together for aftermarket ignition systems requiring +12v while running and cranking.

 

[70chall440]

The blue (ign 1,+12v ignition run only) wire and the brown (resistor by-pass, +12v cranking only) wire have to be connected together for aftermarket ignition systems requiring +12v while running and cranking.

This is correct, if you look at the diagram the connection comes off of the 2 wires because they are connected at the BR. This is something that plaques everyone putting in MSD and/or EFI.

 

[72RoadRunnerGTX]

To be clear, that part of the MSD diagram posted showing the factory resistor/VR wiring is not correct. The blue & brown wires are not connected to the same resistor terminal as originally wired. The VR is not powered through the ballast resistor as indicated in that diagram.

 

[rogue]

+1 to 72RoadRunnerGTX and 70chall440... blue + brown. Note that the 6AL manual says "Ballast Resistor: If your vehicle has a ballast resistor in-line with the coil wiring, it is recommended to bypass it."

 

[moparleo]

https://documents.holley.com/catalog_wiring_diagrams.pdf