MSD 7720 Installation

MSD Power Grid 7 Ignition Control

PN 7720

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Parts Included:

1 - MSD PowerGrid 7 Ignition Controller
1 -

Wire Harness

1 - Parts Bag

WARNING: During installation, disconnect the battery cables. When disconnecting, always remove

the Negative cable first and install it last.

Note: Solid core spark plug wires cannot be used with an MSD Ignition Control.

The Power Grid 7 Ignition Control was specifically designed to pair with the Power Grid System
Controller, PN 7730. This Ignition system is designed for racing applications; it is not for sale for legal
use on highways.

SPECIFICATIONS

Spark Energy: 200 – 220 milliJoules/spark
Primary Voltage: 545 – 570 volts
Secondary Voltage: 50,000 volts plus
Spark Series Duration: 20° Crankshaft Rotation
RPM Range: 15,000 rpm with 14.4 volts
Voltage Required: 12 – 18 volts, Negative Ground
Current Draw: 1.3 Amp per 1,000 rpm
Weight and Size: 2.9 LBS, 7.5”L x 5”W x 2.25” H

GENERAL INFORMATION

BATTERY

An MSD Power Grid 7 Ignition Control will operate on any negative ground, 12 volt electrical system
with a distributor. The MSD can be used with 18 volt batteries and can withstand a momentary 24
volts in case of jump starts. The Ignitions will deliver full voltage with a supply of 10 - 18 volts and
will operate with a supply voltage as low as five volts.
If your application does not use an alternator, allow at least 15 amp/hour for every half hour of operation.
If the engine is cranked with the same battery or other accessories such as an electric fuel or water
pump, the amp/hour rating should be higher.

COILS

It is recommended to use either the Pro Power HVC, PN 8251, or Pro Power HVC II, PN 8261. If you
have any questions concerning coils, contact our Customer Service Department at [phone].

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2 INSTALLATION INSTRUCTIONS

SPARK PLUGS AND WIRES

Spark plug wires are very important to the operation of your ignition system. A good quality, helically
wound wire and proper routing are required to get the best performance from your ignition, such as
the MSD 8.5mm Super Conductor.

Note: Solid Core spark plug wires cannot be used with an MSD Ignition.

A helically, or spiral wound wire must be used. This style wire provides a good path for the spark to follow
while keeping Electro Magnetic Interference (EMI) to a minimum. Excessive EMI, such as the amount that
solid core wires produce, will interfere with the operation of the MSD and other electronics on your car.

Spark Plug Wire Routing: Correct routing of the plug wires is also important to performance. Wires
should be routed away from sharp edges and engine heat sources. If there are two wires that are next
to each other in the engine’s firing order, the wires should be routed away from each other to avoid
inducing a spark into the other wire. For example, in a Chevy V8, the firing order is 1-8-4-3-6-5-7-2.
The #5 and #7 cylinders are next to each other in the engine and in the firing order. If the voltage
from the #5 wire is induced into #7 detonation could occur and cause engine damage.
To add more heat protection to your plug wires, MSD offers Pro-Heat Guard, PN 3411. This is a glass
woven and silicone coated protective sleeve that you slide over your plug wires. For extra protection
of the spark plug boots, MSD offers Pro-Heat Boot Guard, PN 3412.

Spark Plugs: Choosing the correct spark plug design and heat range is important when trying to get
the best performance possible. Since there are so many engine combinations and manufacturers,
MSD does not recommend which plug or gap is exactly right for your application.
It is recommended to follow the engine builder or manufacturer’s specification for spark plugs. With
that, you can then experiment with the plug gap to obtain the
best performance. The gap of the plugs can be opened in 0.005”
increments, then tested until the best performance is obtained.
MSD judges the plug gap by compression and components:

Note: A larger plug gap taxes the cap, rotor and spark plug
wires. Always inspect the cap and rotor to make sure
they are in good condition.

MISCELLANEOUS INFORMATION

Sealing: Do not attempt to seal the MSD. All of the circuits of an MSD receive a thick conformal
coating of Humi-Seal. This sealant protects the electronics from moisture. If you were to seal the
unit, any moisture or water that may seep in through the wiring grommets will not be able to drain
and may result in corrosion.

Welding: If you are welding on your vehicle, to avoid the chance of damage, always disconnect both
heavy power cables of the MSD. (You should also disconnect the tach ground wire too).

Distributor Cap and Rotor: It is recommended to install a new distributor cap and rotor when installing
the MSD Ignition Control. The cap should be clean inside and out especially the terminals and rotor tip.
On vehicles with smaller caps, it is possible for the air inside the cap to become electrically charged
causing crossfire which can result in misfire. This can be prevented by drilling a couple vent holes
in the cap. The holes should be placed between the terminals, at rotor height and face away from
the intake. If your environment demands it, place a small piece of non-metallic screen over the hole
to act as a filter.

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INSTALLATION INSTRUCTIONS 3

MOUNTING

The Power Grid 7 can be mounted in most any spot that would be acceptable for other MSD boxes.
However, if the Ignition is to be mounted with the System Controller paired in the top mounting
position particular attention should be paid to the heat around the units. In this stacked position it is
recommended that the units be mounted inside the vehicle cabin.

When you find a suitable location to mount the unit, make sure the wires of the ignition reach their
connections. Hold the ignition in place and mark the location of the mounting holes. Use a ¼” drill
bit to drill the holes. Install the vibration mounts to the ignition and mount the unit.

The Power Grid System Controller (PN 7730) is designed to
be mounted on top of the PN 7720 Ignition. Be sure to mount
the Power Grid System Controller so the USB connector
and Micro-SD card are accessible. The PN 7730 comes with
thread-turning (aka. Self-tapping) screws that will cut into the
walls of the pre-drilled holes on the top corners of the Power
Grid-7.

WIRING

GENERAL WIRING INFORMATION

Wire Length: All of the wires of the MSD Ignition may
be shortened as long as quality connectors are used or
soldered in place. To lengthen the wires, use one size
bigger gauge wire (10 gauge for the power leads and 16
gauge for the other wires) with the proper connections. All
connections must be soldered and sealed.

Grounds: A poor ground connection can cause many frustrating problems. When a wire is specified
to go to ground, it should be connected to the battery negative terminal, engine block or chassis.
There should always be a ground strap between the engine and the chassis. Always securely connect
the ground wire to a clean, paint free metal surface.

Noise Capacitor: MSD offers a Noise Capacitor or Filter to help eliminate EMI noise. This capacitor,
PN 8830, will also protect the MSD and accessories from voltage and current spikes.

Figure 3 Mounting

ROUTING WIRES

The MSD wires should be routed away from direct heat sources such as exhaust manifolds and
headers and any sharp edges. The trigger wires should be routed separate from the other wires and
spark plug wires. It is best if they are routed along a ground plane such as the block or firewall which
creates an electrical shield.

WARNING: The MSD Power Grid Ignition is a capacitive discharge ignition. High voltage is present

at the coil primary terminals. Do not touch the coil or connect test equipment to the
terminals.

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