1965-1995 Mustang MSD 6A Ignition Box InstallLast Updated December 19, 2023 | Nate Moonis
It's common for your 1965-1995 Mustang to not spark as effectively or efficiently as it ages. This can cause your ride to run poorly and miss out on power. This can be caused by fouled spark plugs, insufficient current reaching the spark plugs, and other potential spark issues. Help your 1965-1995 Mustang run at its best by adding an MSD 6A ignition box.
How to Install an MSD Ignition Box in a 1965-1995 Mustang
Installing an MSD 6A ignition box in a 1965-1995 Mustang is a moderately difficult process that requires you to have some knowledge about wiring including how to properly connect and crimp wires. You'll also need to creatively route multiple wires throughout your Mustang depending on where you mount the ignition box.
It's important to note that this guide is meant for use with the MSD 6A red ignition box and won't necessarily work with other units/brands. The steps and the wire colors mentioned below will be different if you decide to install a different unit.
- Power Drill
- 3/16" Drill Bit
- Screwdriver/Sockets to Match Bolts
- Wire Cutters
- Wire Strippers
- Wire Crimpers
- Wire Connectors
Step 1: Disconnect Negative Battery Terminal
Open the hood and disconnect the negative battery terminal to prevent any shorts or electrical issues from occurring during the installation.
Step 2: Locate Mounting Area
Read the instructions that come in the MSD ignition box packaging, then locate a suitable area to mount the box. This can be in your car's engine bay or interior. We chose to mount ours under the passenger seat of our Mustang.
Step 3: Mock Up Mounting Holes
Set your MSD ignition box into place on the mounting area you found in the previous step. Once you have it properly situated, mark where the mounting holes on the ignition box are located in the mounting area to determine where you'll need to drill.
Step 4: Drill Holes
Use your drill and 3/16" drill bit to drill four holes in the mounting locations you just marked.
Step 5: Mount the Ignition Box
Mount the ignition box in your desired location using the vibration mounts supplied within kit. We used our own screws to secure the ignition box to the floor pan.
Step 6: Ground the Ignition Box
Find a good grounding location on bare metal without any paint or rust for the strongest ground possible. Then, attach the black ground wire coming from the ignition box to the grounding location and secure it properly. We attached the ground wire to the mounting nut on the relay box under the passenger seat.
Step 7: Route Ignition Box Wires
The magnetic pickup on the ignition box is not used for the engine in our Mustang (Ford V8 with electronic fuel injection). Leave the purple and green wire alone and leave the connection wire in the box.
Route the rest of the wires to the coil, battery, and starter area respectively. We fed the wires through the firewall on the passenger side where the computer harness is located. This routing process will be different depending on where you mounted your Mustang ignition box.
Step 8: Feed Wires Through Loom
Tap into the wire loom along the back of the wire wall and route them across the Mustang shock tower on the driver's side.
Step 9: Connect Red Wire
Connect the heavy red wire from the Mustang ignition box to either the battery or the starter solenoid.
Step 10: Strip and Connect Ignition Box Wires
There are two wires that go into the plug on the ignition coil. They will need to be cut. Connect the small red wire from the ignition box to the positive wire coming from the vehicle's ignition. Strip the positive wire and use a connector to crimp the small red wire to the positive wire.
Step 11: Connect Orange Wire
Connect the orange wire from the MSD ignition box to the positive wire coming out of the plug on the ignition coil by crimping them together with a connector.
Step 12: Connect White Wire
Crimp the white wire coming from the Mustang ignition box to the negative wire coming from the vehicle's ignition with a connector.
Step 13: Connect Black Wire
14. Crimp the black wire from the ignition box to the negative wire coming from the plug on the Mustang ignition coil.
Step 14: Set Rev Limiter
After you've connected all of the wires, flip open the silver rectangle that says "REV". There should be two dials underneath the rectangle.
Turn the first dial with a screwdriver to the number (in thousands) where you'd like your rev limiter to be set. Then, turn the second dial to the number (in hundreds) where you'd like your rev limiter to be set. For example, we set our first dial to 6,000 and our second dial to 300 for a rev limit of 6,300 RPM.
Step 15: Reconnect Negative Battery Terminal
Reconnect your negative battery terminal and check for any loose connections on your battery.
Congratulations, you're all done!
Experience Efficient Ignition and Improved Power
With a new MSD ignition box, you're able to effectively monitor and control every firing and rev limit. This allows for improved efficiency and increased power. While not right for every enthusiast, the MSD ignition box might be the right choice for your Mustang if you're looking to customize every little detail of your ride.
If you're interested in purchasing an ignition box for your Mustang but aren't sure if the MSD 6A ignition box is for you, check out our selection below. You're sure to find one that fits your needs and vehicle.