Technical information

AUTOTRONIC CONTROLS CORPORATION • 1490 HENRY BRENNAN, EL PASO, TEXAS 79936 • [phone] • FAX [phone]
www.msdignition.com email: [e-mail]
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Plug Wire TipsPlug Wire Tips
Plug Wire TipsPlug Wire Tips
Plug Wire Tips
To keep your engine’s
spark plug wires in tip-top
condition there are a few
simple steps you can take.
For starters, apply a small
amount of MSD Spark
Guard, PN 8804, a dielectric
grease, to each wire termi-
nal. This keeps any moisture
out of the boot while lubri-
cating and insulating the ter-
minal-to-plug connection. It
also aids in pulling the plug
socket off without tearing the boot or wire.
Extra protection from heat is always a good idea. MSD
wires have a very durable sleeve but in applications with
tight engine compartments and close exhaust systems,
additional protection is a benefit. MSD offers Pro-Heat
Sleeve, PN 3411, a silicone coated woven glass sleeve
that slides over your wires for added protection. If you're
looking for protection around the boot MSD's Pro-Boot
Guard, PN 3412, is the answer. This is an extra thick
sleeve of woven glass with a silicone coating and will
protect the boot from excessive heat.
Another important point to consider is the way the
plug wires are routed. Using good wire separators is a
key in preventing inductive crossfire which occurs when
two wires that are consecutive in the firing order are
run next to each other. MSD offers a variety of Separa-
tors that will help position the wires away from exhaust
manifolds and sharp edges while keeping the engine
compartment looking good.
Note: Distributor caps that re-route the wires to the
left and right are not recommended with an
MSD Ignition Control.
Spark PlugsSpark Plugs
Spark PlugsSpark Plugs
Spark Plugs
Choosing the correct spark plug design and heat
range is important when trying to get all the perfor-
mance possible. Since there are so many engine com-
binations and manufacturers, MSD cannot recommend
which plug or what size gap is exactly right for your car.
It is recommended to follow the engine builder’s or
manufacturer’s recommendations for plug heat range
and gap.
Once a proper plug is selected, you can experiment
with the gap to get the best performance. By using these
recommendations as a starting point, you can experi-
ment by opening the gap in 0.005" increments then
test. When the performance falls off, the gap is too large.
Carbureted or fuel injection engines can use larger gaps,
but turbo or supercharged engines should stick with
the smaller gap. If no significant gains are achieved, go
with the smaller gap. Remember, the larger gap taxes
the plug, wires, cap and rotor.
After changing the gap,
reading the spark plugs is
a helpful tool in getting the
right tune up. The air/fuel
ratio and how it’s burning
can be read on the ceramic
portion of the spark plug.
A ring can be seen where
the effective heat transfer
takes place. The closer this
ring is to the tip, the richer
the mixture. Closer to the
base of the plug means the
engine is running more
lean.
SPARK PLUGS WIRES AND SPARK PLUGS
Rule of Thumb Plug Gap
COMPRESSION GAP
UP TO 10.5:1 .040 - .045
10.5:1 - 13:1 .032 - .040
OVER 13:1 .025 - .032
Note: These are recommended for normally
aspirated engines only. Reduce the gap for
blower, turbo or nitrous applications.
Coil Wire Routing
In some applications, the coil is mounted in the pas-
senger compartment of the car. In this case, the coil
wire must be routed through the firewall. To prevent
voltage leaks, use an MSD Firewall Feed-Thru, PN 8211,
8212. This provides 1/2" of insulation and keeps the
spark from jumping to ground.