Struggle a bit to understand why the current runs this way through the plugs?

Hi Viking.

What bit don't you understand? Is it the actual direction of the arrows, or is it that it goes in one plug and out the other?

If it's the former, then I reckon the arrow direction is pretty academic - I think they are simply demonstrating that there's a complete 'loop' involving both plugs. (If you swapped the HT leads around, then it would go the other way, but would still work just the same.)

When the 'points' open, the magnetic field that was built up collapses instantly and this sends an electrical pulse back out the primary coil in the opposite direction to that it went in (I understand the main job of the 'condenser' is to absorb this large pulse and prevent it arcing a burning the points.) The much higher induced voltage in the secondary coil will also come out the opposite way to the pulse when the coil was switched on (points closing). (I think there may also be a 'spark' when the points close, but it's a relatively small one, and its timing means it has no effect on the ignition.)

So, the arrow direction is largely irrelevant - I think it's just to show what's happening. If you have something against that particular direction, say, for political reasons, then swap your HT leads or the primary coil wires

(There's also the small matter of actual current flow and 'conventional' current flow...)

Yes why does it show serial connection and not parallel.

With a 'normal' car coil, the primary is fed from the +ve from the ignition switch, and the -ve of the primary goes to earth via the contact points. Then, with the HT secondary, one end of this winding is, I presume, permanently earthed and the '+ve' side feeds the single HT lead and distributor. All the HT pulses have the same polarity and come out the 'top' of the coil and feed the distributor, then the spark plugs in turn and then back to earth.

On a normal car the plugs get their sparks with the same polarity, and the wear (spark erosion) at the plug terminals occurs in the same place. With the 2CV system, the polarity at each plug is different, and the wear therefore takes place in different places - on the centre terminal on one, and the side terminal on t'other.

So I'm guessing that is the reason for better starting/running, if you swap the low tension leads over? The plugs are firing on different points on their tips.

I guess that should even out the wear on both plugs so's it occurs the same on both...

In theory it shouldn't matter which LT lead goes to which terminal on the coil, but I'd be tempted to keep it the way 'it was'!

What you could do, however, and I think it makes sense, is to swap around the spark plugs every time you take them out to check and adjust.

D.A..
I find that swapping the coil connections over is much easier than removing the plugs for re-gapping, which is only needed about every 5,000 miles.

If the leads are reversed each time the kingpins are greased, that saves having to keep notes as well...

ken

Cheers, Ken - it's good to have confirmation that reversing the LT coil connections is ok!

I just wasn't sure, so didn't want to say