Distributor cam

[Vyv Cox]

My Lomax 223 has a Boyer Bransden ignition system. Being a newcomer to Citroen 2CV engines I assumed that what I have is the standard arrangement. Due to persistent poor running I decided to change to a 123 ignition, which I have purchased. When it arrived I opened up the existing BB ignition, assuming that the 123 would be a straight swap, but found that there was no distributor cam. I put a request for one on Small Ads, which met with some confusion. My further research reveals the reason.

The arrangement I have now is shown in these photos.


I now see that this is unusual. The nearest I can find to it on Internet is a You-tube video of a Triumph motorbike, which appears very similar. I am guessing that what I have is a special, with a modified camshaft made to fit the BB rotor. Can anyone please confirm that this is so?

I assume that the standard arrangement is this one that I found on a French website, apparently with the magnets for the 123.


I have ordered a distributor cam, awaiting delivery. I suspect that my only option is to make up a new central boss to replace the existing one, enabling me to fit it to my camshaft. Any other suggestions? Or have I got it completely wrong?

[cmwbob]

Vyv, the problem I see you having is knowing at what angle to fix the new part to any new centre boss you make up. As that has to be pretty close for timing adjustment.
Assuming the made up boss that you have has been set up to work with the BB setup then I am guessing the timing on that is pretty close to being right. So would it not be better to make up two steel plates to slot into the grooves of your existing boss with a screw hole for fixing and then a suitable stub to take the 123 magnet.

[Vyv Cox]

There are no slots, keyways or any other registration. The BB rotor is put onto the shaft loosely, the motor at firing point, the rotor is then turned to match the hole in the stator plate. The nut is tightened and timing should be achieved. It took me about an hour to do this!
With the 123 it is possible to rotate the stator (without the bolts) until the LED lights. It should then be possible to rotate the rotor to the same angle. Could even be less than an hour.

[notsmartcar]

Is there an oil seal where the camshaft passes through the crankcase

[cmwbob]

Hi Vyv, I wrongly guessed then that the 4 small notches in the back flange were locating points for the BB magnet adaptor.
So I agree the 123 led feature will prove invaluable to you

[Vyv Cox]

I assume there must be an oil seal as I have driven well over 2000 miles in the car and rhe cavity is perfectly clean. The engine does not drop oil.

[administrator]

Vyv,
Unless I've got the wrong end of this stick, the points cam is not what you need. It would be attached to the lugs in photo 3 via the spring weights which provide advance and retard - if using the original points-based system. These are thrown away when fitting 123 as the weights attach directly to the posts shown in photo3 and the advance is done electronically.

You need the plate and posts that are pressed onto the end of the camshaft - or make an equivalent plate and posts that attach in the same way that your BB plate currently attaches. You'd have to rotate it through trial and error to get it close, but then rotating the 123 unit would give you the final adjustment.

As for oil seals, the cam shaft utilises a scroll to keep the oil where it belongs....

Rgrds
Callum

[rocketronbish]

H there...complicated problem ! I have a number of spare 2CV cams . If it would be of any help I could let you have one for £10 plus postage.
Regards Ron 01225335777

[Vyv Cox]

Callum,
Thanks for the input. Photo 3 shows a distributor cam (the part with the two lugs attached, given different names according to the source). I do not have this. In photos 1 and 2 my camshaft seems to have been modified to take the BB rotor disc. I suspect I could mount the distributor cam on this but it would then be destroyed. I intend to turn a new centre boss to fit the new cam when it arrives, to mate with the existing camshaft.
All this after the 30-30 event, which we are looking forward to immensely.
Vyv