How to Wire an MSD Ignition

A multiple spark distribution (MSD) is a type of capacitor-discharge ignition that delivers a series of high-voltage sparks over a longer duration than a single spark coil ignition. This brings about a much more complete combustion of the fuel, resulting in more power. Exercise care when the hood is open and the engine running; an MSD can jump a considerable arc and deliver a serious shock.

Things You'll Need

• Drill
• Set of drill bits
• ¼-inch drive ratchet
• Set of ¼-inch drive sockets
• Wire crimping tool
• Box of assorted wire terminals
• Wire loom
• Voltmeter

Instructions

1. Determine the location for the MSD box. The box can be inside or outside the vehicle. If the box is to go under the hood, the location should be safe from the elements, open so that it can dissipate heat and in the coolest spot away from the exhaust manifold. Place the box where it will be mounted, and mark the location of the mounting holes in the MSD for reference. Make sure that it is a safe spot to drill without damaging any components.

2. Drill the holes, then place the MSD box with its rubber bushings over the holes. Insert the bolts and tighten with the 1/4-inch ratchet or an appropriate-sized wrench.

3. Route the black and red 10-gauge wires to the battery, attaching the red wire to the positive terminal and black wire to negative terminal. Plan the routing to avoid heat sources and conceal the wiring. Install wire loom over the wire for protection and aesthetics.

4. Connect the smaller 16-gauge red wire to a switched power source such as the ignition switch or fuse block. Use a voltmeter to confirm that the power source switches on and off with the ignition key.

5. Connect the wires to the coil, with the orange wire going to the positive terminal of the coil and the black wire to the negative. Connect the wire or wires to the triggering source. If your vehicle has a standard-point type distributor, attach the white wire to the singular wire on the distributor. If the vehicle uses a magnetic pickup in the distributor or a crank trigger, use the green and violet wires.

6. Attach the tachometer to the small spade terminal on the side of the MSD box. Connect the harness with the plastic connector to MSD-related equipment such as a delay box, if applicable. Adjust the rev limiter by placing the correct rpm chip in the side of the MSD. The MSD will come with several rpm chips for different rpm limits--pick the desired chip and push it into the receptacle on the side. The MSD will automatically shut the engine down when the rpm is exceeded, by shorting out certain spark plugs.

Tips & Warnings

• The spark plug gap can be widened when using an MSD ignition by .005.

• Keep your hands clear of all spark plug wires to prevent accidental shock.