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PostPosted: Wed Jun 03, 2009 6:15 pm 
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Joined: Tue Mar 16, 2004 8:55 am
Posts: 11265
Location: Geelong, Victoria
I picked up one of the electronic points kits for the 25D distributors from EBay UK. It comes in at a little under fifty dollars delivered, which is pretty reasonable coin if you consider a set of points and condenser will cost you just under $20. Without anything to wear or adjust they reduce distributor maintenance to just about zero. They also eliminate any problem with points bounce or cam wear; and, by eliminating the side load introduced by the heavy points spring, extends distributor shaft bearing life.

This kit is for a 25D or 29D distributor. The car must be -ve earth, although +ve earth cars can be provided for as well with a specially ordered version.

These are apparently significantly upgraded from the very early blue module kits. The heat sinking abilities are much better with the transistor bonded onto an internal plate and bonded to the base, and the inclusion of a sachet of heat transfer paste in the kit.

You can see from the image below that the main electronics of the points module is screwed down onto the baseplate. This means they can reuse the same module on many different designs of distributors without creating a new production line for the many different points configurations. Good thinking.

In the picture you can see the rubber plug to suit a 25D (early mini) distributor on the leads from the module. Unfortunately this plug doesn't suit a 29D (Mk2, early clubman) type distributor; but it’s no problem because there is an easy workaround.

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This is the kit as supplied from the UK. Included is the module, a set of leads, heat transfer paste and cable tie and the ring which will trigger the Hall Effect electronics. You will reuse your own cap and rotor arm.

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First job is to remove the points and condenser from the distributor. I have taken the dizzy out of the car as the engine timing will need to be rechecked, so I might as well make the job a little easier by doing the job out of the car. Mark the distributor location using a permanent marker or a scratch from a file; then loosen the nut which can be seen above the center line of the image above. This will allow the dizzy to rotate and pull out from the engine nice and easy.

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Once the points are out, clean (using sandpaper if required) the base plate inside the dizzy. This is very important as heat from the new module must be able to transfer onto this plate. Like electricity, heat prefers a clean contact surface.

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Remove the wire which connects the distributor to the coil. On the 25D it slides up and out, on the 29D it pushes through into the distributor. I needed to push it in using a screwdriver as the plastic is a little stiff.

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For a 25D distributor, the job is a little easier. The plug provided will slot right back into the dizzy and you can step straight over the next few steps. For the 29D dizzies, you will need to remove the provided wiring plug as it is of no use to your dizzy at all. I cut mine away carefully until the wire insulators were exposed and simply pulled them out. If you cut into the wire a little, don't fuss, they are only low voltage and can be repaired with a little heat shrink.

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29D continued: You will be left with a hole in the side of the dizzy which will need to be sealed to keep moisture out. Moisture will cause the dizzy to short the high voltage from the coil to ground when running, so it’s important to plug this hole.

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29D continued: The hole is a half inch in diameter, so pick up a 1/2 grommet from Autobarn, Repco, Supercheap or similar and punch two small 1/8th holes side by side through the bung to allow the two wires to pass through. I removed the terminals from the supplied plugs to get them through the grommet. This is easily accomplished as they are held into the plugs by small tangs of brass adjacent to the metal contacts. Use a thin screwdriver or tweezers to flatten the tang and withdraw the connector. Alternatively, cut the plug off and use your own connectors.

Push the wires through the side of the dizzy and push the grommet into place. A screwdriver pushing the rubber at strategic points makes this a lot easier than doing it with your fingers. If the grommet holes are nice and tight then this seal should be enough.

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25D and 29D continued: Before the module can be put in place, the heat transfer paste is applied to the underside of the electronic points module. This paste helps to improve the efficient transfer of heat from the module to the base plate. The Darlington pair transistors create a lot of heat in operation and are sensitive to large temperatures over 150 degrees Celsius. The dizzy temperature in operation will reach 80 degrees on its own from the water jacket, so there is not a lot of room for error here. Once they burn out, they are burnt out for good. Hence the cleanliness required on the base plate and the need for the heat transfer paste.
How much? Use enough to cover the entire underside completely with a smear, but not so much that it squeezes out in the sides of the plate once attached. This stuff is like a creeping grease and will migrate all over the distributor in short order. Over time it will collect grime which is something to be avoided inside a dizzy and may cause high voltage tracking to earth. So keep the coating light, but consistent as I have in the image below.

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Tighten the module down using the original screw which formerly held down the points. The module will slide over the post that the old points used to hinge on. There is some play here but this is not important for this module. Before tightening, place the trigger ring over the dizzy shaft and push down into position. It will lock into place on the top of the old points cam. This ring has four magnets which will trigger the hall effect device within the points module.

Adjust the module using the tie down screw above to approach the trigger ring to within a half mm gap, but not touch it. It must not contact the module in any way or failure may occur in use. Again, the actual specific gap is not significant, as long as it doesn't come too close to touch.. Once tightened again, spin the shaft to ensure the trigger ring cannot contact the module.

Replace the rotor button and reassemble the dizzy back into the car using the mark you made on the base plate to align the dizzy back to its original location.

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Connect the wiring up to the coil using the cables supplied, or create your own terminals. As I wished to keep it as low key as possible and because I have a Smiths Tachometer, I created my own customised leads to hide the extra wires.

Wiring is simple. Stick to the rules and don't mix it up.
Red wire to the + (plus) terminal on the coil.
Black wire to the - (minus) terminal on the coil.

Use a multimeter to check that the +12 volts goes to the +ve terminal on the coil if you aren’t sure. Engines can run with them back to front, but it will destroy your new module. Remove the connections from the coil before doing so as there are conditions in the distributor (when connected) which can make your multimeter reading confusing if the terminals are left connected.

The red is easily seen, it goes to a male spade connector I have sandwiched beneath the top one to keep the wires a little neater. You can't see my black wire in the image below as it connects to a wire going to my inductive Smiths tachometer; the white wire is the return on the -ve post from there.

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Re-align the dizzy and once the car starts; reset your timing to match the setting in your maintenance manual.

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