No spark.

[Ray White]

A duff condensor affects the ability to create a good spark. Various things are possible.

But this sounds like a dead short in the rotor arm. 

Hold the king lead near the head and spin the engine on the starter. You should get a cracking lively spark. Then with the rotor arm in place hold the king lead near the rotor arm and spin the engine. You should get no spark jumping to the rotor arm. If you get a good spark jumping to the rotor arm then there is a dead short within the rotor arm, and it needs a new one.

Do I look for a spark jumping to the centre contact spring on the rotor arm?  

Will this work the same if I just flick the points as I can't operate the starter AND see what is going on...or do I have to persuade my long suffering wife to operate the starter.?  (SWMBO doesn't share my interests and only likes new cars. _)

[Jeff Taylor]

And Ray, if you need to buy a new rotor arm, buy a red one from the Distributor Doctor or one of his suppliers.

http://www.distributordoctor.com/red-rotor-arms.html

[Andy Bennett]

Ray
whether or not you need them all at this time I have always found it helpful/reassuring to carry a set of ignition consumables (cap, points, lead, arm, condensor, plug). They aren't heavy/bulky or overly expensive and they give you the opportunity to swap them out 1 by 1 to see if they are faulty in times of somewhat mysterious faults. You are also going to need them at some point so never a waste. Noting that some new components fail out f the box so they don't always confirm something isn't faulty, just that it was if things return to normal.
When some things fail when hot or after running, or just intermittently it is much easier to swap out that try to catch the moment of fault.
So my suggestion would be to buy a new set of everything whatever the outcome of this fault finding process.
Andy

[andrew34ruby]

A duff condensor affects the ability to create a good spark. Various things are possible.

But this sounds like a dead short in the rotor arm. 

Hold the king lead near the head and spin the engine on the starter. You should get a cracking lively spark. Then with the rotor arm in place hold the king lead near the rotor arm and spin the engine. You should get no spark jumping to the rotor arm. If you get a good spark jumping to the rotor arm then there is a dead short within the rotor arm, and it needs a new one.

Do I look for a spark jumping to the centre contact spring on the rotor arm?  

Will this work the same if I just flick the points as I can't operate the starter AND see what is going on...or do I have to persuade my long suffering wife to operate the starter.?  (SWMBO doesn't share my interests and only likes new cars. _)

Do I look for a spark jumping to the centre contact spring on the rotor arm?  ......   Yes.

Will this work the same if I just flick the points   ......  You can try flicking the points, but it's better to get someone to pull the starter.

[Ray White]

And Ray, if you need to  buy a new rotor arm, buy a red one from the Distributor Doctor or one of his suppliers.

http://www.distributordoctor.com/red-rotor-arms.html

Yes indeed, Jeff.  I have always found Martin Jay to be most helpful.  He once managed to find me a very rare set of points that fit my original Rist distributor.  I seem to remember that at that time (quite a few years ago) there was not a red rotor arm to fit.  I will ask again.

---

Ray
whether or not you need them all at this time I have always found it helpful/reassuring to carry a set of ignition consumables (cap, points, lead, arm, condensor, plug). They aren't heavy/bulky or overly expensive and they give you the opportunity to swap them out 1 by 1 to see if they are faulty in times of somewhat mysterious faults. You are also going to need them at some point so never a waste. Noting that some new components fail out f the box so they don't always confirm something isn't faulty, just that it was if things return to normal.
When some things fail when hot or after running, or just intermittently it is much easier to swap out that try to catch the moment of fault.
So my suggestion would be to buy a new set of everything whatever the outcome of this fault finding process.
Andy

Hello Andy.   It would be nice to be able to get a replacement distributor cap because I still have most of the original C.A.V.  ignition set.  However, I don't think that will be possible unless one turns up at an auto jumble.

 The DS4 distributor is round with the condenser clipped to the outside.  Unfortunately the original brown rotor arm failed some years ago and had to be replaced with a modern black plastic replacement which has worked fine up to now. The points are different to the Lucas ones and interestingly the cap and leads are brown in colour.  

The 6v 'Rist' coil is shorter and fatter than those currently available (you don't see them now)  and has a brown bakelite 'nose' with push in HT lead fittings.  I have purchased a new 6 volt REMAX coil from the Green Spark Company; it looks far too "bling".!

Incidentally, Trundles is a very original car.

[Ray White]

SHE RUNS!!!!!!

The problem I had must be linked to the fact that the ammeter needle which normally shows a slight discharge when I switch on was not moving at all.  This time when I switched on the needle showed signs of life and she fired up instantly.  Perfect tick over. 

Perhaps the ignition switch needs some tlc.?

Thanks to everyone for their help and advice.

[A G Wood]

All good Ray!
Hate those self-rectifying faults...I think if I were in your shoes, then yes, I'd be having a really good look at the switch. Sounds like intermittent excessive voltage drop across it, as you said at one stage you had a spark at the centre lead but nothing out of the distributor (and I gather the rotor is fine) low primary voltage=low secondary voltage. Maybe loose/corroded terminal issue? Also might be worthwhile making a jumper lead with crocodile clip ends long enough to jump the coil 'SW' terminal straight to battery live and by-pass the switch and wiring if it happens again (esp if it happens again in an awkward situation)
Regards
AGW

[Ray White]

One thing I did at some point was replace a frayed low tension cable where it connects to the coil. There were only a few strands holding it on!.. I hadn't seen it because it was being shielded by the plastic insulation. I had been meaning to remove the insulation for ages but never got round to it. It now has a nice soldered ring connector which is both sound and blends in well.

I am thinking I may have fixed the problem without even realising!

I have some long jumper wires with crock clips that I take with me in the car. They live with other spares that I hope to never need.


Ray.

[John Cornforth]

Hello Ray

I know this thread has sort of finished, but I have been on holiday and couldn't log in to reply.

Reading from start to finish, I think your problem was/is high resistance in the contact breaker points.  When things are working properly, the points carry about 4 amps whilst closed, and their resistance should be no more than 0.05 ohms so they will drop only 0.2 volts.  This corresponds to a power of (4 x 0.2) = 0.8 watts.  Since they are only closed for about 50% of the time, that makes an average power of 0.4 watts.

I can't imagine 0.4 watts (or even 0.8 watts if the engine is stopped with points closed) dissipated in a lump of metal like the points assembly being anywhere near enough to cause a large temperature rise, certainly not enough to burn fingers !  If they are really hot, either you have a short and they are carrying more than 4 amps, or their resistance is much higher than it should be.

High points resistance will of course cut down the coil primary current and weaken the spark.  With the coil's king lead held near earthy metal and the points flicked, you should have enough voltage to jump a gap of 100 thou (i.e. much more than an ordinary spark plug gap) as the spark is only under atmospheric pressure.

I have often found that after a lay-up, the points acquire a high resistance film of tarnish and or white corrosion.  For some reason, this only seems to kick in after you have driven for a couple of minutes.  The tarnish/corrosion can be quite hard to remove fully. One effective method I have found is to draw very fine glasspaper between the points a few times, then flush out with switch cleaner aerosol.  A final draw through with fine card soaked in switch cleaner completes the process. Without the switch cleaner flush, the insulating residue seems to stay sitting in the points gap and holds the two faces apart.

In theory, one should avoid emery paper as it leaves behind abrasive and electrically conductive particles.

In the car toolkit I keep a small fine grade "diamond spatula" which is easy to use and lasts indefinitely.

[Ray White]

Hello John. Thank you for your considered advice. I will have another look at the points and clean them again. your suggestion to use switch cleaner sounds like a game changer.

Thank you...and every one who has contributed.

Ray.