Pictures and information by Karl Schluter. Copyright.
Make
you own magnetic Lucas distributor!
Mkl,ll
Consul and Mkl-lll Zephyr, Zodiac Models.
You can fabricate your own
magnetic trigger system inside you present older Lucas distributor if its
bushes etc are sound and you can find donor parts compact enough to fit inside.
Wreckers or car dismantler yards would be a great place to recycle a few parts
and check out donor systems to adapt whether for just the single parts or a
complete donor distributor as described further on. You will also need the
donor cars matching module/amplifier. Wire these items as per the cars
manufacturer and use a matching electronic coil. Also read the section on
polarity below.
Lift the cap on some
Chrysler Valiant, Ford electronic Aussie, NZ, US, and European models (Bosch
and Motorcraft ) and some Japanese distributors. On the shaft under the rotor
is often a reluctor which looks like a toothed cog (this is where your older
points cam would be), it has the same number of teeth as cylinders in the
engine the item is fitted too. A Pick up (a small coil on a magnet) is mounted
near by on what would be the points vacuum advance plate. The pick up coil gets
a signal from the toothed cog (reluctor) that then triggers the module to
spark.
Before removing the reluctor
and pick up coil unit from a distributor, measure the air gap (there's a
picture below) between the furthers edge of a reluctor tooth, to the pick up
coil (Use a brass or plastic feeler gauge). This air gap is to be kept once
these parts are installed in the Lucas distributor.
Some Auto Electrical places
sell Japanese/Bosch pick ups plus Summit and Jegs mail order shops sell a Ford
type pick up and reluctor separately, (made for MSD ). They are fairly
priced too.
Note: I have chosen the
Magnetic system as a conversion because it is one of the most common and
reliable.
Below is a basic guide that
outlines how to convert a Lucas points distributor:
Install:
The parts must not foul with
the fit and movement of the rotor or the base of the vacuum advance plate (make
sure when mocking up that everything clears).
The Zephyr distributor
points cam lobe area can be bushed or machined to have a donor toothed reluctor
slipped over it (make sure the reluctor is centred correctly), the
workshop manual shows how to remove the cam lobe assembly. Have a provision to
lock the reluctor in place with a setscrew or a hardened pin after
the following mounting of the pick up coil on the points plate is completed.
Remember to have the right tooth count reluctor, if working on a 4 cylinder,
use a 4-tooth reluctor (a V8 reluctor can also be used if every other tooth is
removed), otherwise for 6 cylinder cars a 6-toothed reluctor is used.
It’s important in the next
step that the manufacturers air gap from the donor distributor is kept (below).
This is the air gap between the tooths furthest point and the pick up coil as
stated by the donor manufacturer. Use the air gap taken as mentioned above when
these parts were first removed. If you don’t have the measurement or brought
these parts new, look up the correct air gap in a workshop manual for the donor
car at your nearest library.
Set the
pick-ups base on the vacuum advance plate (the same place as points would
mount). Keeping the correct air gap as mentioned between the reluctor and
magnetic pick up coil, (use a brass or plastic feeler gauge) mark the pick up
coil base mounting holes. Some, but not all, pick-ups have an adjustment slot
like a points base. When you mark the hole in this slot, mark it midway to
allow for later air gap adjustment either way.
Then remove the now marked
vacuum advance plate (after removing the reluctor) and drill and tap the plate
to mount the pick up coil.
After mounting the pick up
coil to the points vacuum advance plate, install the plate back in the Lucas
distributor body (or screw the pick up coil on after reinstalling the advance
plate) and then put the donor reluctor back on and secure it in place with the
set screw etc, (Do not fully lock the reluctor in place until you have covered
the need for rotor phasing as mentioned later). Recheck the air gap and add
your cars rotor. Make a last check by turning the shaft of the distributor by
hand to check that everything clears inside, sometimes you can feel the pull of
the magnet.
Phasing:
Phasing is the alignment of
the rotor to the spark plug terminal when a spark is fired.
Why bother with Phasing? A
high power ignition spark will be more likely to jump to another terminal than
the one its suppose to go too if phasing is out, more so in a small cap. This
is why most performance caps are wider between terminals now if room allows. A
wider placement of the spark plug terminals in the cap helps to ensure the
spark from the rotor goes to the correct plug, thus minimising a misfire. This
leads to a smoothing running engine at higher rpm as well.
Because in a vacuum advance distributor the vacuum advance plate is
moving due to engine vacuum, correct phasing is more of a compromise. Aftermarket
distributors without vacuum advance are checked and set at the factory.
How to check phasing:
This step is often over
looked in modifying distributors and even factory systems can be out of phase.
Setting the Lucas distributor on the 4th line of its vernier vacuum
canister scale as mentioned above in the points section sets a Lucas point
system up close. There is a number of methods to check phasing. The mechanical
advance (weights and springs) does not change the phasing as the rotor to points
cam (or rotor to reluctor/shutter) relationship does not change. It’s hard to
get it exact on a vacuum advance distributor as this setting changes as the
vacuum advance plate moves, it is still however worth checking.
To do a converted
distributor you need a basic timing light and a spare sound distributor cap.
Drill a 3/8 or bigger hole (slowly with a smaller pilot hole first) carefully
between the coil post and the (any one) spark plug terminal, you may
decide instead to section the cap as in the picture below. You need
to drill closer to the spark plug terminal (to be able to watch the rotor tip
inside) or the caps side if you can view it easy enough once its clipped in
place, pick a terminal with room around it to view inside of as the engine runs.
Highlight the centre of the
rotors tip with “twink” or a dab of white paint. Clip the timing light lead
onto the spark plug lead terminal that has the hole drilled next to it.
1,Carefully watching for
moving parts, focus the timing light into the distributor cap hole with the
engine running at idle speed and the vacuum advance line unhooked and plugged,
the rotor should be to the RIGHT of the spark plug post (before the terminal
going anti clockwise), mark the rotor position on the edge of the cap (use a
felt tip pen etc).
2,Then with the vacuum
advance line hooked back up and the engine at a fast idle, note the rotor
position with the timing light again, it should now be to the LEFT of the spark
plug post (after the terminal going anti clockwise) and re-mark it.
The idea is to later adjust
it (if needed) so it would then in theory be pointing at the spark plug
terminal mid way through the full range of vacuum advance (between both marks).
Estimate the amount of degrees distance the rotor would need moved (and in
which direction) to equal its spacing on either side of the spark plug
terminal, with both the vacuum connected and unconnected (plugged).
Note: The rotor itself will
hopefully not need to be repositioned, instead its position is being noted
solely as a guide to show whether the phasing is out etc .The rotor phasing
position will only need moved in one of two directions to even it up.
How to adjust Phasing:
With most models of Lucas
distributors we are lucky to have the vernier dial on the outside body that by
turning it (the dial) carefully will move the points mounting plate (now
mounting the pick up coil). This changes the position of the pick up coil
relative to the reluctor cog, in turn changing the timing of the spark firing
as the rotor aligns with the spark plug terminal.
Adjust the
phasing if needed (engine running and timing light shining into the cap) by
turning the vernier dial to set the distance/direction you have estimated the
rotor needs to move (the rotor position should move as you turn the vernier
dial either way).
If this method does not
bring the rotor into the correct setting,
1,Reposition the reluctor by
rotating it a degree or two on the distributor shaft in either direction,*
2,Reposition the pick up
coil on the vacuum advance plate (maintaining the correct air gap)
3,File the base of the
distributor caps locating slots and turn it a few degrees in either direction.
4,Die grind out the locating
tab inside the rotor, and use epoxy to make a new tab to relocate its position.
*Best of these 4 options.
Afterwards you can recheck
you rotor position as described above, vacuum hooked up, and then unhooked
(plugged).
NOTE: The
above works ONLY for distributors turning ANTI CLOCKWISE (like
Consul-Mkl-lll Zephyr,Zodiac), reverse the rotor positions if working on
CLOCKWISE turning distributors.
Polarity:
The pick up coil has
polarity! Wire the two wires from the donor pick up coil as per the cars wiring
diagram for that donor models distributor first. Or follow the
Aftermarket modules instructions for that Donor distributor parts manufacturer.
If the timing is way off on
crank up, or the engine won’t start, try swapping over from side to side the
two wires from the distributor pick up coil at its plug, this is more common if
an aftermarket module/spark box is used. Keep these two wires away from the
ignition coil or spark plug wires. Running the wires next to the frame or steel
items can help stop EMI inference as can twisting the two long wires together
as they exit the distributor body. The magnetic pick up coil often has a third
wire, black in colour with a “Ring” terminal that is usually earthed to the
engine block etc. Do check for this.
Continued in Ignition
Upgrade Part 4
Do visit the Ignition Upgrade Part 5 for links, companies etc.
Disclaimer:
The advice and guidelines given in these articles are given in good faith.
The owners and managers of the Galeforce Zephyr site will take no
responsibility for any injuries or loss sustained while carrying out the
described tasks and procedures or any consequences arising. Please read
the Safety First
Article