MSD 7805 8-Plus Ignition Control Installation - Manual (Page 2)

2 INSTALLATION INSTRUCTIONS
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GENERAL INFORMATION
BATTERY
An MSD-8 Plus Ignition Control will operate on any negative ground, 12 volt electrical system with a
distributor. The MSD can be used with 16 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.
If your application does not use an alternator, allow at least 30 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
The MSD-8 Plus Ignition must be used with an MSD Pro Power Series Coil. The Pro Power HVC, PN
8251, Pro Power HVC II, PN 8261 or for short duration racing, the PN 8201 Pro Power Coil. If you
have any questions concerning coils, contact our Customer Service Department at (915) 855-7123.
TACHOMETERS
The MSD Ignition features a Tach Output Terminal on the terminal strip. This terminal provides a
trigger signal for tachometers, a shift light or other add-on rpm activated devices. The Tach Output
Terminal produces a 12 volt square wave signal with a 20% duty cycle.
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 Heli-Core or 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.
MOUNTING
The MSD can be mounted in most positions. It can be mounted in the engine compartment as long
as it is away from direct engine heat sources. It is not recommended to mount the unit in an enclosed
area such as the glovebox.
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 1/4” drill
bit to drill the holes. Install the vibration mounts to the ignition and mount the unit.
TACH
TERMINAL
Figure 2 Tach Terminal.