I'd really appreciate suggestions.

The 1983 Charleston (with fairly recently installed 123 ignition) has just developed a dreadful misfire/power-loss problem. It'll tick over, reasonably well, though maybe stall (though it will restart). But if I try to put any load on the engine it goes into extreme power failure, usually followed by, or accompanied by, loud banging in the exhaust. I managed to drive it the last few hundred yards back to the holiday cottage I'm staying at, but it really wouldn't get further.

I assume if it bangs in the exhaust that's unburnt petrol getting through. When the fault first developed, two days ago, and in a more minor form, on cold start running it was hesitating badly, then picking up revs (but not banging in the exhaust, I'd guess because it wasn't hot enough).

The power failure is intermittent but permanent (apparently) - that's to say the engine will run for a few seconds, or even as much as a minute, reasonably well, but then dives off into no power at all - but without actually stopping, usually.

Any suggestions where to start looking? By replacing the old points ignition? I'm fairly sure I still have them.

Could it be fuel/carburation?

Dennis,
it could be carburettor related, if any of the jets were blocked, but the fact that it's intermittent suggests that the fault may lie with the newly installed ignition setup.
That's where one of these would come in handy, giving you the capability to check if there's a strong, regular spark...
http://www.ebay.co.uk/itm/AccuSpark-pai ... SwN81XNco4

First thing I would do would be change the plug leads ......I've had those symptoms, and dud plug leads were the reason.....[several times]
Again, a set of these [as recommended by Ken] are well worth carrying.

Failing the plug leads being the prob, I would then replace plugs & coil [one item at a time, that way you'll find just exactly what was causing the prob] ......before suspecting the 123.
Are all the connections & terminals tight on the 123 .....I've had the terminal work loose on my "Lumenition" module, and that too will cause misfires.
My moneys deffo on it being "Ignition Related".
hth
T.

First an apology. The 123 ignition was in my dreams - a job I'd meant to do but not got around to. Old age is my excuse.

So it was old-fashioned points after all, and to cut a long story short it was the condensor.

A helpful friend tried a good coil. No difference. He also looked into the carb and decided it too was OK.

When I planned swapping back to the original points and found there wasn't an electronic ignition unit after all, all it needed was to replace the points and condensor with some second hand ones to bring it all back to life.

I now plan to put in a new set of points and condensor, and new plugs, and do the timing properly......

Thanks for the suggestions just the same!

If you've got an old condenser on, and it works, leave it there. New ones are very unreliable now unfortunately.

Has anyone worked out yet why these new condensors are so unreliable?
My moneys on a bit of "EU Directive" bumbling, fumbling & fudging ....the old ones are prob'ly either carciogenic, or interfere with TV's and old ladies hearing aids.....or perhaps its part of the great plan to make us buy a new car every 6/8/10/[?] years.
T.

Terry,
the capacitors used for ignition systems tend to consist of aluminium foil plus greased paper insulation, in a sort of 'Swiss roll' configuration, so I'd doubt that the EU could have any possible influence on how they're put together.
Companies choosing to have their components manufactured at the lowest possible cost are much more likely suspects,don't you think?

Ahhhh .....we can blame the "bean counters" then.
Although, tbh,I've had Luminitition EI on my 2CV since the mid 1990's ....[so its never been an issue AFAIC].
T.

I was offered a "new" (newly manufactured) condensor by that helpful friend - he apologised that it wasn't a proper Ducellier one.

The metal barrel wouldn't even fit inside the plastic cylinder that holds it to the points box. That really must have been a cheap manufacturer.

Is/was Lumenition a better system than 123? Easier to fit?

Don't talk to me about timing .... grumble grumble .....