BUILD AN ELECTRONIC IGNITION!

Articles supplied by Jilden

BUILD AN ELECTRONIC IGNITION!

• Many P76 owners have fitted aftermarket electronic ignitions to their V8’s.Some have fitted modified distributors from other engines, e.g. Chev. Some people have found an elusive Valiant V8 Lucas electronic distributor and fitted it with the relevant module off the Valiant.
• I have always resisted these options due to their cost, up front, and the cost or unavailability of replacement parts when they pack up. I wanted cheap, common replacement parts. Lucas caps and rotors count, as they also fit the Rover V8.
• Recently I got to rummage through the box of old distributors in the local wrecking yard while hunting for another job, when I found a Bosch V8 Valiant distributor. I got it for nothing and took it home. It had a spiky rotor where there would be a points cam, and a magnetic pickup which mounted very simply to what looked much like a points plate.
• I took a reasonable P76 distributor and ground off the points cam, as it was case hardened steel. Then I machined it down to a press fit for the spiky rotor. I machined out the hole in the centre of a spare base plate to clear the rotor, to save having to remove the rotor when dismantling the thing every time I modified it. Then I took the pickup and modified it a little to fit the base plate with a single screw and nyloc nut. The wires pass out of the original points-wire hole.
• Next I connected the pickup wires to a Bosch 024 module, mounted on a separate aluminium bracket, and a high energy coil. It worked a treat! The distributor has been in my car for a month now and really packs a good spark.
• Previously I had fitted one of these modules to a Chev distributor which had blown up its third Delco module in a year, and it was very successful. The Bosch module (part no. BIM024) is very common in Australia, having been fitted to XD to XF Falcons, VC and VH Commodores, Magnas, and other cars between 1980 and 1986. They run a variety of M.E.I. and H.E.I. coils straight off 12 volts.
• Another visit to the wreckers found another Valiant distributor, so I started on another one. This time, my spare P76 distributor had a very worn advance mechanism, so I took out the two shafts and compared them. The Valiant shaft was slightly longer and exactly the same diameter! With the P76 one as a pattern, I re-drilled the shaft roll pin hole and filed new pump-drive flats on it. The only trouble was to work out how to machine the rotor button mount to fit the Lucas part. I made a small mandrel in the lathe and pressed the cam on it and machined it carefully. Now I had a Bosch mechanical advance mechanism in a Lucas case! This distributor has just gone into the Wagon.
• A phone call to a mate raised another Valiant dizzy, which was made into a P76 one and is going into Margaret’s car next week. The beauty of this job is that I have finally found a use for the old cannibalised distributor collection, freeing up some complete ones to keep as spares. The cost has been limited to new modules at $50 each, and new coils for $45 each when I couldn’t find any more at the wreckers. I also found that Sigmas of the late 70’s use the same pickup coil, so I got one for a spare.
• Keep on P’ing! Jilden.

ELECTRONIC IGNITION (PART TWO)

• In my last article, I described my conversion to the V8 P76 distributor using a Valiant V8 reluctor to drive a Bosch 024 module. Two things have come up about the conversion, namely, I don’t use vacuum advance for LPG, and that Valiant V8 distributors are too hard to find.
• When I tried to make a conversion for a friend keeping the vacuum advance plate, I found I couldn’t do it. There isn’t enough height. So, I rang up my trade supplier for a Holden reluctor to suit the blue V8 motor. It came up at $87 for genuine Holden, $126 for the same part in a Bosch box. Just goes to show that you can’t check prices enough.
• I then machined the P76 distributor case to centre the reluctor as accurately as possible, as these have very little operating clearance. It has to be set lower than the points plate, and needs screws outside of its mounting plate to hold it in. I machined off the points cam as before, except I also had to cut a vertical groove for the reluctor centre plate to locate on, and circlip grooves above and below it, 4.5mm apart. The vertical groove has to be located correctly for timing, i.e. when the rotor is near a spark lead terminal. I found that the vacuum advance unit off a points Holden distributor fits straight onto the reluctor with an ingenious stop arrangement to prevent it falling off in service. It wasn’t hard to fit onto the P dizzy case.
• So I have ended up with another working electronic distributor, the difference being that all the needed parts can be bought new. All up trade price for the parts is about $200, with about $50 labour to machine the distributor.

INTERESTING NEWS INTERESTING NEWS INTERESTING NEWS

• Along the way, I have discovered some interesting repair possibilities for the P dizzy. The “spider” clip which holds down the points plate is very similar to the one in the Sigma distributor. I bent up the legs one and filed a notch in one leg to hold it in place. It looks good!
• The plastic bush which is supposed to hold the points cam onto the shaft is easily replaced. Cut the clip end off the main shaft, drill and tap a 4mm (or 5/32”) thread into it, use a suitable screw and washer and that’s it. This makes dismantling and rotor removal so much easier.
• The rotor itself has a bore of 14.25mm (nearly 9/16”) according to my vernier calipers. This just happens to be the same as the rotor for the Ford XC-XE 6 and V8 electronic distributors. I looked carefully at the Ford item, and discovered it is a little higher than the P76 one, but a little shorter (0.5mm). Height can be cut down, and the length is fixable as the brass strip is SCREWED ON and can be removed. Slot the holes, replace the brass strip, and you have a new replacement part in your hand. Move the strip by 1mm and reduce your end gap. This reduces backfires on LPG. Saves waiting days for one to turn up in a country town. Its part number is GB786.
• Long live the mighty P76!
• Jilden

More clues on electronic ignitions

• A call for help from member Paul Hobbs made me realise an oversight in my first article in June on high-energy ignitions.
• The magnetic pickup that I used from a Valiant or Sigma distributor has two coloured wires. The Bosch Module requires a pulse of the correct polarity to fire it, On the module, the small terminal (No. 3) has to be connected to the orange wire from the pickup. Otherwise, the ignition will fire very reluctantly and with retarded timing.
• Using the Holden V8 reluctor as described in August, the wires are fitted with different sized connectors to make it obvious which way to connect it.
• Problems have been encountered with even slightly loose connections; the system can’t tolerate them. I recommend squashing all crimp connectors slightly to make them really tight.
• The module must be mounted to a good heatsink with the supplied special grease, otherwise it will get very hot and fail.
• Another change I made was to run a new, heavy-duty wire direct from the ignition switch to the coil. While I was there, I fitted a hidden kill switch in this wire. I taped back the crummy little wires to the loom in case I wanted to go back to standard ignition.
• Jilden.

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