Very wise words Rick, as usual. I would add that MSD's help in an engine
that is not perfectly tuned is hard to ignore. And yes, the lower the
octane, the faster the burn, so adjust timing accordingly. But the multiple
spark thing insures about as full a combustion as possible providing several
factors that came to light during my own investigation of matching the MSD
to Edelbrock headers and a slightly modified motor while conversing with the
folks at MSD, Edel, and even Champion.
One, avoid platinum plugs at all costs since these have a tendency to retain
heat and can lead to premature failure. Lumped in these are all those fancy
plugs that proclaim a hotter spark, heat indexes, shmeet indexes.
Next, probably the most overlooked factor in matching plugs to heads, even
stock, is how far they go into the cylinder. With HP heads this could mean
the piston actually slamming into the plug. But on OEM heads, it is still
important to insure proper depth for optimum ignition, depending on the head
design. You don't need a LOT of spark, but it has to be consistent and at
the right place at the right time. At higher REVs (+4000), and MSD is
vastly superior.
Do NOT assume that a Delco plug matches better to a GM head, or Autocraft in
a Ford. Surprisingly, these are often poor matches. Go figure.
Champion plugs' electrodes are notoriously off center. This is a
manufacturer defect across all of their lines and has been so for many
years. I had to go through 30 to find 8 on center, and that was on the gold
ones. The good thing about champions is that they offer a tremendous
selection of heat indexes, and depths (yes, they are related) in various
forms.
An MSD set up generally requires a wider gap than normal, typically above
.40, no matter what plug.
Here are some other tidbits, mostly anecdotal and completely my opinion..
You can place the box behind the pass side headlight, there is a opening
there to allow air flow and these boxes do not like high heat or water.
Spring for the MSD with rpm limiter and comes with vibration mounts, etc.
It is only a few bucks more and even protects rides with A/Ts on bad
launches and such, provides better cooling of the box, yada, yada.
If using an MSD, don't skimp on the wires! I've tried a bunch over the
years, I don't like ACCEL 8.8s, as they deteriorate faster than a Spring
thaw. Take an ohm reading of the wire when new and a month later. I've
seen mine increase 10x. No more 8.8s. Mallory or MSDs seem pretty
compatible.
hmmm, letsee, ....
stephan #2821
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