Mallory Ignition Mallory 4-STAGE RETARD CONTROL 678 - Manual (Page 2)

Additional Functions:
The 678 Controller has two more functions that can make the
ignition installation and setup work better. One of these is the
high-speed advance function. This lets you put small amounts
of timing in the engine after the torque peak to pick up a bit of
horsepower. There are three things that need to be set up for
this: the cut-in RPM (mode 9), the maximum advance (mode A),
and the slope (mode 8). The cut-in RPM is the RPM where you
want the curve to start working. The slope is how much the
timing will advance every 1000 RPM after the cut-in RPM. The
maximum advance is the highest amount of advance you want
the system to reach.
For example, say that your engine has the torque peak at 6500
RPM, and you want to add some timing after this. You might
want to start adding timing after 7000 RPM, so this becomes
your cut-in speed. If you then want 2 degrees additional timing
at 8000 RPM, then the slope would be set for 2 degrees per
1000 RPM. However, let's say that you don't want more than
2 degrees of advance, so you would set the maximum advance
at 2 degrees, See example 6 for more detail.
The other additional function available is trigger compensa-
tion, which is set when the mode indicator is "b". This lets you
compensate for the various delays in ignition timing caused by
both electronic and mechanical changes. To set the trigger
compensation, set mode 9 to 5000 RPM, and mode 8 to zero.
What this does is tell the system to start the high-speed
advance at 5000 RPM, but with a slope of zero, there should
be no advance. Once the system is set up this way, watch the
timing as the engine revs past 5000 RPM. If the timing does not
stay at a steady value (once the 5000 RPM point is reached)
then adjust the compensation value until it is as flat as possible.
For example, if the timing retards slightly as the RPM goes up,
increase the compensation value. If the timing advances slightly
as the RPM goes up, decrease the compensation value.
NOTE: This function is only valid for RPM above the high-speed
advance cut-in RPM. If you have the high-speed advance cut-in
set above the normal operational range of the motor, the
compensation function does nothing.
Once the compensation is set, then the high-speed advance
settings will be accurate. The factory setting should be correct
for most types of flying magnet type crank trigger systems, and
should not normally need to be adjusted unless you are using a
different trigger type.
Number of Cylinders Selection
The final mode that can be set is mode "C". This allows you to
select 4 through 12 cylinder operation. This ensures that the
RPML and the timing are proper for the engine. Mode 6F is
special - this is for odd-fire V6 engines ONLY! The cylinder
firing spacing should be 45/75 (at the distributor) or 90/150
at the crank.
NC
N
NO
RPM2
RET1
RET2
RET3
RET4
COIL
To +12 Volts To Nitrous System
From Nitrous
Activation Switch
COIL
To Ground
CONTACT
CONTACT
RELAY—Use a relay if you are
switching more than 3-5 amps.
RELAY
NC
N
NO
RPM2
RET1
RET2
RET3
RET4
To Ground
To +12 Volts
www.mrgasket.com MALLORY IGNITION 2
EXAMPLE 1: Using the RPM switch (Mode 7) to
turn OFF a nitrous system at a
particular RPM.
EXAMPLE 2: Using the RPM switch (Mode 7) to
turn ON a shift light.