Electronic Ignition

NB: The product mentioned in this article was the choice of the author and is cited for accuarcy of reporting.  By including this information CA7C, its committee and members do not imply recommendation, or endorsement, of the product.  Anyone wishing to fit electronic ignition to their Austin Seven must satisfy themselves as to the suitablity of any product.

 
Having searched the internet and failed to find any tips on fitting electronic ignition to an Austin Seven, I offer this solution in case there are any other eccentric Austin hobbyists out there just waiting to try it.
 
Last year I was having problems with the ignition system of my 1938 Opal.  After fitting new plugs, swapping the coil, condenser, distributor cap and rotor arm to no avail, I finally cured it by replacing a relatively new set of points.  Considering that my wife’s Morris Minor runs very nicely on a cheap electronic ignition set-up, I thought I would experiment with the Austin.  Yes, I read the advice not to waste time on it.  I also couldn’t easily ignore the tale of woe from the Rolls Royce people whose very expensive 6 volt electronic ignition systems packed up after a couple of thousand miles.  I do respect the view of those who told me that this was a solution to a non-existent problem.  But the spirit of adventure prevailed.  I wanted the electronic ignition to be in-keeping and as far as possible invisible. It's also why I didn't go down the popular route of a Bosch distributor or 12 volt electrics.
 
Where to find a 6 volt system?  Anybody who trawls the internet will find an American unit that’s used on 6 volt tractors.  There’s a firm in the UK who will sell this device setup for an Austin Seven, but at about £160 incl VAT and postage the price was seriously off-putting.  I was also concerned whether it would work with a bit of voltage drop (for example whilst cranking an Austin engine) and for this sort of money I wasn’t willing to find out.  This also happened to be the same device that persuaded the Rolls Royce guys back to their conventional condenser and points.  So I had to look further.
 
I eventually found Ignition Car Parts Ltd who claimed they could fit their 6 volt kit into a DK4 distributor for £45.  The module actually looked identical to the one in my wife’s Morris Minor.  Anyway, armed with my DK4 dizzy and a spare base plate, I visited the firm to have them fit the electronic trigger unit, magnet ring and special rotor arm.  When I went to pick it up, it was on a test rig sparking away quite happily at just over FIVE volts.  OK, step one completed.
 
Back home it was a 20 minute job to fit the distributor and temporarily adapt the wiring.  An electronic unit needs one extra wire and some re-arrangement of the others.  I adjusted the static timing by rotating the distributor and using a strobe light to see when it sparked.  Having fitted a pointer next to the camshaft pulley (as explained in another article) it was a fairly easy process.  Step two completed.
 
But the engine wouldn’t start.  Cranking it on the starter and pointing the strobe at the pointer I could see that the ignition timing was wildly over-advanced.  After checking and re-checking it statically, the spark was clearly advancing itself when the engine was cranked.  Then if I rotated the distributor far enough to get the timing right, the rotor arm was nowhere near the contact for number one plug lead.
 
I decided that the electronic ignition module wasn’t in the right position relative to the magnet ring that fits over the distributor cam.  All I had to do was to move the module around the magnet ring to get it to trigger whilst the rotor arm was pointing at number one plug.  By taking the feed to the strobe light directly from the coil, I could leave off the distributor cap.  I then used a dab of 'Blu-Tack' to hold the module in place whilst moving it progressively clockwise until the strobe flashed on the timing mark at cranking speed.  No doubt I could have done it more scientifically with a protractor and slide rule, but I was still baffled why static timing should have worked, but didn’t.
 
Now came a bit of engineering work to drill and tap holes in the base plate to screw the module in place.  After re-checking the timing at cranking speed and replacing the distributor cap, it was fingers crossed for a new attempt at starting.
 
Although the battery was down after all the cranking, the engine fired and ran immediately.  The timing needed very slight adjustment followed by fine-tuning on the road.  It worked perfectly.  Step three completed.
 
Elect Ign 1All that remained was to tidy up the installation.  The electronic unit fits inside the distributor cap and uses the standard coil, so no problems there.  But as mentioned above, there is one extra wire.  I threaded this through a small hole in the distributor base plate (drilled through the overhang at the back) and routed it back to connect up with the ignition switch wire, which has to be disconnected from the coil.  The other wire on the coil is swapped to this empty SW (negative) terminal.  The CB terminal (positive) is then connected to earth.  This one extra wire and the earth connection isn’t something you would notice unless you were hunting for it (and maybe not even then).  The part that called for some creativity was the other distributor connection.  The original wire from the coil to the distributor can be re-used, and you are supposed to connect this to a wire coming through the condenser screw hole at the side of the distributor.  This didn’t look right, so I found a setscrew and nut with the same thread as the condenser, and connected the internal module wire to it inside the distributor.  Then I attached the original coil wire with nut and washer to the outside, so it looks identical to the standard condenser terminal.  I hope it’s clear if you look at the photograph of the distributor innards.  The second (red) wire exits through the hole drilled in the back of the base plate.
 

Elect Ign 2

This is the complete conversion.
 
I haven’t detected any increase in performance or reduction in petrol consumption. The engine doesn’t start any differently.  I do like to think it’s running a bit smoother.  But that wasn’t the reason for doing it.  The objective was to fit and forget.  No more changing the points.  No more fiddling with feeler gauges.  No more worrying about the condenser.
 
But just in case, I still carry the old base plate in the spares kit with condenser and points set up.  Two minutes to revert back to conventional.
 

 

Another electronic ignition system sold by Boyer Bransden system is completely different in operation.  It retains the original contact breakers but adds a solid state switching device to eliminate arcing.  So the points don't erode over time. It is more a case of electronic assistance than pure electronic. The downside is that you still need the points and you have to hide the small transistor box away somewhere. On the plus side you don't have to carry around a spare baseplate and rotor arm in case the electronics fail. It's also much easier to fit, considering that I had quite a job finding the correct position for the electronic unit, then drilling and tapping the baseplate to mount it.  Mind you, for an Austin man this might just be part of the fun.  And the switching is completely solid state, which is what I was really aiming for.
 
I didn't get an Ultraspark part number.  I just asked for a 6 volt positive earth unit to fit to a DK4 distributor. Also please don't overlook the fact that it didn't work as delivered.  Electronically it was fine, but I had to re-orientate the unit on the distributor base-plate to get it to spark at the right moment.
 
Ignition Car Parts Ltd
Unit 16 Ilford Trading Estate
Paycocke Road
Basildon Essex SS14 3DR
website: http://www.ignitioncarparts.co.uk/Content.aspx?page=UltraSpark
 

Also:

Boyer Bransden Electronics Ltd
Frindsbury House
Cox Street
Detling
Maidstone Kent ME14 3HE
website: www.boyerbransden.com

 

This article, written by Jim Callus, originally appeared in CA7C Seven Focus in February 2012 pp 22-24.

Our friend Jim Callus is an Englishman living in Holland and is a member of the Dutch Pre-War Austin Seven Owners Club.


NOTE:   Electronic distributors replacing the Lucas DK4A are now available from specialist supplieras, see 'Guide to Parts & Services' > Distributor Electronic.and Ignition Electronic



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