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TIPS
 | With a new O-ring seal, the 123 distributor may be difficult to fit
into the engine housing. A liberal application of grease to the seal and a
bit of force will ensure the distributor slips into the hole.
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| You can wire the 123 distributor straight to the coil, bypassing the
white/black coil lead from your Mini's wiring harness: black to -ve, red to
+ve.
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| If your engine develops an intermittent misfire under load, you should
replace the ignition coil. A weak coil that just barely functions with
points will fail when pushed by the electronics in the 123 distributor
which switches the coil on and off much faster.
|
| Tests have confirmed that clean spark signals are generated well above
8000 crank RPM. if a high-speed misfire occurs at very high engine speeds
look into the efficiency of the charging system: it should be able to
deliver around 10 amps at 13 volts to the coil for the duration of the race. |
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Any engine running on the street should have the vacuum advance hooked up.
This is a fuel economy feature which is in no way detrimental to engine
performance. For race engines you may choose not to use it, but unlike
mechanical distributors, there is no risk of the advance mechanism locking
up and causing an over advance condition.
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| The vacuum advance is for normal PORTED vacuum, not MANIFOLD vacuum. If
your engine is equipped with a side draft Weber you will not be able to use
this feature as it has no vacuum port. When not in use, the vacuum port on
the distributor can just be capped.
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| Mini's, being what they are, rarely survive with their original
distributor or engine specification. If you do not find a suitable
description in the application guide you can
use the tuning guide. NOTE! You should have
some idea of what you are doing since it is possible to select a curve that
will deliver too much advance and damage your engine.
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| The 123 distributor is designed to be static timed at TDC which gives fixed
timing of 10˚ BTDC up to 1000 RPM for easy checking. If you feel you need
more maximum timing, change the curve, not the static timing position.
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| The 123 distributor is NOT user programmable. The market has many
products that allow user manipulation of the ignition advance curve. We are
offering a plug-and-play solution to the user that does not want, or need,
to get heavily involved in engine optimization.
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| Although 123 distributors are much less susceptible to ingress of water,
an ignition shield is STRONGLY recommended for any Mini. The standard ROVER shield used on late model Minis
works very well. |
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Some applications have very little clearance above or ahead of the
distributor cap. A right angle cap can be fitted to the 123 body with a
small amount of grinding. Find out how here.
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A word about ignition coils
| Check the resistance of the coil across the primary terminals. Coils with
resistance of ~3Ω can be operated at 12 volts. Coils with resistance of
1.5Ω or less are 6 volt coils and must be used with a ballast resistor
in line with the ignition switch. Ballasted coils were used from about 1974 onward, but they can be found on any vintage car now. They
operate at 12 volts to deliver a hotter spark while the starter is engaged,
then drop back to 6 volts when powered through the ballast resistor. The 123 will fire either ignition coil and will operate on the 6 volt feed
from the coil. |
| Continued operation of a 6 volt coil at 12 volts will overheat it and
cause it to fail. If your coil is designed to work with a ballast resistor,
that resistor should be fitted.
Coils generally do not fail completely, but work intermittently
which is a difficult problem to trace. |
|
Aftermarket coils can be internally ballasted, meaning they have 12 volts
supplied to them, but internally they operate at 6 volts. If you have one of
these make sure the external ballast resistor is bypassed.
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| Do not use coils with resistance less than 1Ω. These draw so much
power that they can damage the 123 circuitry. Street engines do not need
lightning bolts to fire a cylinder charge unless there is something
desperately wrong! |
A word about ignition advance curves
| An ignition advance curve is designed to light a fuel-air charge and place
the peak cylinder pressure at around 18˚ ATDC. This is a mechanical
requirement of all internal combustion engines, but the time it takes an
engine to develop that pressure is a function of engine design and operating
conditions. A change in any mechanical parameter, particularly one that
affects volumetric efficiency, will require a change in ignition advance
curve.
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| Modern fuels are completely different from when BMC series engines were
built, so it's expected that an optimized ignition advance curve will, as
well, be different now. If the engine works well enough with the factory
curve, stick with it, but some experimentation may be beneficial in terms of
performance.
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| The ignition advance curve in a worn Lucas distributor will not be the
same as when it was produced and the mechanical advance mechanism may not
even be working. It's very likely that the vacuum advance unit is
nonfunctional after 40 years of service.
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| Old school tuners sought the holy grail of distributors: the 23D4 service
number 40819 from the Mini Cooper S. The curve in this distributor has to be
the strangest duck in the entire line! It is claimed to be right for 970,
1071 and 1275 S engines even though the only thing in common between these
engines is the bore diameter. Fact is, it's wrong for all of them, but the
curve is so slow that it's safe for all of them, no matter the state of
tune. 123/Mini curve 'C' is an approximation of the 40819 curve should you
want to try it out. |
A word about applications
| Numerous questions have been received about whether there is a curve in
the 123/Mini for an engine (usually based on a 1275) with such a cam and
head and rockers and pistons.... YES! We have designed the curves exactly
because there is no such thing as a stock A series engine! Please consult
the tuning guide for some suggestions on where to start. These curve
families were designed to be logical so the process of homing in on the
right curve for your engine is relatively rapid. No other distributor can do
this as simply or quickly as the 123/Mini. None. |
A word about benefits
| The 123 distributor will not 'make' more horsepower. Power is made in
the engine so all a distributor can do is ensure the engine makes all the
power it possibly can by firing the fuel charge at the right instant.
|
| A freshly rebuilt mechanical distributor with points will be at its
optimum for a very short time before the breaker points start to
deteriorate. Because the 123 is all electronic, it always
delivers optimum ignition performance.
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| Recurving an antique Lucas distributor is an arduous task because springs
are no longer available; you have to make your own. It's impossible to know
how the curve is changing if you don't have access to a distributor machine
which is an increasingly rare tool these days. The 123 will precisely
deliver the curve selected without having to find a distributor machine.
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| No animals were harmed in the design, testing or manufacture of the 123
distributor line. I'm sure you were wondering. |
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