MSD 7222 7AL-2 Ignition Control Installation - Manual (Page 3)

INSTALLATION INSTRUCTIONS 3
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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.
Initial Spark: It is normal, yet not very common, for the MSD to produce a spark when the ignition
key is turned On. This is due to the capacitor being charged and if the pickup is in the right position,
it could trigger the ignition momentarily. This could also occur when installing the positive battery
cable.
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.
These examples are just starting points to
get you going in the right direction. Every
application is different and should be
tested and tuned.
Compression Spark Plug Gap
Up to 10.5:1:
0.050" - 0.060"
10.5:1 - 13.0:1: 0.040" - 0.050"
Above 13.0:1: 0.035" - 0.040"