Pre War Distributor Units

AlanBartlett · Post by **AlanBartlett** » Fri Jul 13, 2007 8:16 am

Are they available from jowett car spares? Because I'm not getting a powerful enough spark for combustion. Ive traced it to the dizzy unit because Ive borrowed a working coil unit and its just not generating enough electricity for a big enough spark, even testing the plugs at a 12 thou gap

george garside · Post by **george garside** » Fri Jul 13, 2007 10:18 am

have you checked the condenser (capacitor) in the distributor. easiest way is to substitute a known good one if you have one. I don't know for certain but there may be a readily availble 'modern(ish)' one oavailable that can be substituted as all cars had them prior to universal employment of electronic ignition. just take the old one to an accessory shop/motor factor & try to identify one that will fit your distributor. The only other thing I can think of is either the carbon brush in the distributor cap is missing/faulty or the cap itself is cracked shorting the current that should be going to the plugs - again substitution is the easiest way to 'test'
but bear in mind Sods law that dictates that if you a spare cap, condenser or whatever it may also be faulty!
george

AlanBartlett · Post by **AlanBartlett** » Fri Jul 13, 2007 10:41 am

Hi george,

The cap is indeed a little cracked well missing a little corner, would that make a difference then? also is the capacitor the little cylinder shaped thing which u connect the wire from the coil to?

george garside · Post by **george garside** » Fri Jul 13, 2007 1:36 pm

yes its the little shiny (at laeast when new) cylinder that fits inside distributor & is connected to the points. it should have a wire from one end and a bracket with screw hole at the other end where it is attached to the baseplate. As to the missing corner this in itself should not prevent starting but it may be a sign that there are hairline cracks in the cap itself allowing current to go where its not wanted instead of down the high tension leeds. Just another thought - have you cheked the high tension leeds themselfes - again substitution is the easiest way to do it/
george

AlanBartlett · Post by **AlanBartlett** » Fri Jul 13, 2007 1:39 pm

Hi George,

Ok cheers just making sure we are on the same wave length, also the ht leads i have replaced completely so there shouldnt be a problem with them. I will head to my local car shop in a mo and see what they can figure out about it .

Alastair Gregg · Post by **Alastair Gregg** » Fri Jul 13, 2007 4:19 pm

You seem to be progressing well, just a thought condensers store charge for days sometimes weeks after use. It is unlikely to kill but will hurt. Discharge the wire to ground (holding wire with insulated pliers) before removing condenser.

I hope you get this post before you discover the shocking ability a condenser has.

AlanBartlett · Post by **AlanBartlett** » Fri Jul 13, 2007 4:29 pm

For now I've left it with the car shop so they can track down another one, I know this is a stupid question but what is the job of a condenser, alistair quoted about it storing charge? but im not exactly sure what it does?

Alastair Gregg · Post by **Alastair Gregg** » Fri Jul 13, 2007 4:30 pm

Check out 220128614706 on ebay. I don't knbow if its the right one but it looks good.

ian Howell · Post by **ian Howell** » Fri Jul 13, 2007 6:42 pm

'Click' on 'View Previous Topic'.

Bryan Walker · Post by **Bryan Walker** » Sat Jul 14, 2007 12:59 pm

Hi Alan,
The condenser (Capacitor) is to help stop the burning out of the points as they open by absorbing the excess energy (Back electro Magnetic Field (EMF) that is generated in the coil and which tries to keep the flow of current through the points going resulting in the arcing of the points. Condensers are like 2 sheets of foil separated by a thin dieletric
(insulator) this has a habit of drying out over time or breaking down giving a secondary path to earth for the coil. so that the build up of energy LEAKS back to earth via it resulting in weak spark.

Alan, Check the resistance of the earth to the points with a digital voltmeter on ohms(ignition off), and with the ignition on and points open measure the voltage at the points, about 9volts as the low tension side of the coil should read between 3.1 to 3.5 ohms on a 12volt circuit - or about 1.43 to 1.58 ohms on a 6volt circuit- you should have about 6volts at the points. If not turn of the ignition and trace the circuit with the ohms meter looking for any resistance i.e were the wire joins onto the Dis. from the coil.

After this still no luck test the High tension side- First remove the wire going to the distributor cap from the coil at the cap end. Then, use your insulated handling devise to see if you get spark when an assistant cranks the engine over, if you do not get a good, strong spark, either the coil or coil lead is bad. Replace the lead and try again. If still no spark, replace the coil. If good spark you can the do the same test with each spark plug lead but use a long bolt or screw in place of the spark plug. If not the leads and is into the Dis. replace the cap and/or rotor.

PAUL BEAUMONT · Post by **PAUL BEAUMONT** » Tue Jul 17, 2007 1:20 pm

Alan, I suppose you have done the simple things like cleaning the points? Every time I start my Bradford for the first time after the winter I have to take the points out and clean them well or I get no spark or a very poor one. I have now fitted new points and am getting much more reliable service.
That said you do not need much of a spart for the thing to run - maybe not well but it should fire up if you have some sort of a spark.

george garside · Post by **george garside** » Tue Jul 17, 2007 1:27 pm

Alan, just another thought on the 'simple things' . Have you put new petrol in as the modern veriety seems to go off very quickly if stored.My petrol mower instructions recommend not more than 4 weeks old for goood starting! might be best to run a plastic tube from pump straight into a gallon can so you are sure of a clean fresh petrol supply
george

AlanBartlett · Post by **AlanBartlett** » Tue Jul 17, 2007 1:44 pm

Hello, Right heres the dilema, still no spark, replaced the capcitor, tried the thing where you connect a plug to the coil and turn on handle slowly, this results in a spark, also flicking the closed points (no spark), I'm running out of thoughts as for the petrol I only use a small amount in the tank so fresh is put in regualarly I will try and clean and reset the points how would I go about this, although they were replaced a couple of weeks ago for better ones I will give it ago.

Keith Clements · Post by **Keith Clements** » Tue Jul 17, 2007 4:17 pm

If you are getting a spark at the coil; but not on any of the plugs then surely it is the distributor cap or rotor arm or even HT lead from coil to cap.

Tony Fearn · Post by **Tony Fearn** » Tue Jul 17, 2007 7:01 pm

You said you've replaced all the HT leads. Did you bare the ends, put the plastic terminal screw on the lead and feed the exposed wire through the little copper split washer with a hole in it and splay it out before you screwed the terminal screw back into the distributor cap?

Also did you make sure that the distributor cap terminals are nice and clean?

What's at the plug end? Is it a push on plastic plug end which you've screwed into the wire core at the end of the HT lead? If so, undo it and see if the screw in it has actually been in contact with the wire.

If you've used a metal spade conection, did you make sure that the wire was well-soldered on to it before you attached it to the plug?

I agree with Paul (and others) about having clean points. It's a must. Set them at about 15 thou and with the ignition off push a petrol-wetted fine cotton rag between them to make absolutely sure they're oil/grease free, then do the same with a clean dry piece of the same rag.

Finally (for now), and don't take this wrongly, are you sure that every time you've checked for a spark you have actually turned the ignition on?

Tony.

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Pre War Distributor Units

Pre War Distributor Units

Condenser discharge.

Distributor Cap