Sorry, very late, but here is the manifold with, engine plate, dynamo mount, & bodged up carb mount...

Looking at it, I'm not sure an AMi 6 carb will fit. I think the distance between the 2 bolts are smaller then at my Ami... I will try to find some time and measure mine (hopefully tomorrow)..

I've heard rumours that on cars fitted with 123, there can be a problem with the engine running on only one cylinder, but have only experienced that myself when the coil was an Accel type, also when conditions were damp and the HT was able to arc across to the metal mounting straps.
Changing the straps for one rubber ones or using plastic tie wraps cured that problem.

You will not be able to determine which cylinder is 'lazy' by removing a lead.
The spark on these double-ended coils relies on both leads being in place for the high tension circuit to be completed; the electrons flow down one lead, across the air gap in one plug, through the engine mass and back to the other end of the coil's secondary winding through the other plug lead.
In fact, if you do remove a lead whislt the engine is running, you're running the risk of damaging the coil's internal insulation, since the HT will seek out the 'path of least resistance'.

How about a compression test? If one cylinder is low on compression, it can take a while for it to 'light up' after a cold start.

Had to make a testdrive anyway, so here are some pics of my Ami 6 from 22 februari 1963..
and some pics of my back-up engine...

The distance between the 2 (carburetor) bolts is about 60mm (as far as I could measure with the carb on it)....

Whats the distance between your bolts???

I've got the same at my 51 AZ.. (running on points and 1950-ties aftermarket coil) Pulling 1 lead for just 3 or 4mm makes the engine suddenly run on 2 cilinders.... The only thing I can come up with that the newer leads have to less resistance for this coil..

I cured it with a second window plugcap???? where you can see the spark arcing, don't know how it's called in English...sorry..

p.s. it is always the same lead which I need to pull...


I have no issues with 1-2-Spark with this (at least none of my costumers replied) but still only at 12 volt....

Thanks Ken that is a very useful bit of info - I have pulled leads off in the past willy nilly! Don't recall it always stopping tho, perhaps those coils were already mullered?!
what is that please? Coil is a bog standard black, oil filled, one, infact it is 2 of them as I've switched them around trying to isolate the fault - with no obvious difference. I see Roy is offering a dry version of the black coil, is this the same as the ECAS super coil but looking 'original'? And is it better than the oil filled one - price is the same?
On the question of compression; my tester is playing up, I got a reading of 152psi off the left pot but the tester then refused to hold pressure & I could not get a reading off the right one. Not got round to fixing or replacing it yet (this was Christmas eve; just too late to ask Santa!) but is right @ top of the list.

Good pics Geo, thanks - I will measure the studs tomorrow.
I binned a new set of plug leads as they seemed to be giving the poor running on the M4 and on this 425. but not so sure it was the main cause now. This engine was certainly happier with it's tatty old leads so I guess the wrong resistance in the new leads might have had a bearing on it...?
Can't think what the name of the 'window caps' is but I know what you mean
12v is fine here - changing to 12v was half the start of this problem!! I want 12Spark for my M28 come the spring anyway

I've got a compression tester if you want to borrow it? I'm about all weekend, could drop it over.

I have the chinese made resin filled (dry) type. Been fitted a few months. No problems so far. I have kept my Argentinian 'oil filled' in the boot just in case.

i had a starting problem too after fitting the 123. After it had run a short while it did so all day without any problems. It turned out to be one of the connectors not sitting thight on the plug. After a short moment engine and plug warms up and the connector fitted nice. I pinched the thing a bit and it functioned nice since. But last autum i was cleaning it up a bit and it turned out that the same connector was completly rotten away. It might have been sparking between plug and connector all that time?? So i had to put in new cables. Strange huh?

Thanks for that guys!
Poss that was the problem with the new plug leads, a bad contact... I'll have a poke about with those.
Next time I need to buy a coil I'll try a dry one