what causes this?

[davidmiles]

Total and unexpected ignition fail this morning, loads of electrical power, nice strong starter motor action, loads of fuel that came out of the filter when I checked it, then the rotor arm with this burned edge, could that be the cause of my ignition failure? or do I need to check deeper?[frame][/frame]

[JOWETTJAVELIN]

Do you have electronic or points?

Could be a faulty condensor.

[bmcecosse]

Normal - give it a wee rub with glass paper. Look elsewhere for the problem....

[smithskids]

I once had a rotor arm fail, you could see the electrical tracking line across the bakelite as it went to earth

[lambrettalad]

my first port of call would be condenser ,do u have a spark ?at the plugs, at the points do you get a light when testing?

[davidmiles]

thanks guys I'll check that. thanks for the replies.

[JOWETTJAVELIN]

I also recall there was much grumbling about some red rotor arms on the forum in the past. Perhaps yours is one of the poor quality batch?

[davidmiles]

My dizzy is electrical not points, would that effect the rotor arm and prevent ignition[frame][/frame]

[JOWETTJAVELIN]

Couldn't say myself, as I've always used points, but I understand if electronic ignition goes wrong then it's kaput.

Someone will be along who knows about electronic ignition.

[mogbob]

David
I switched from your restoration post to this one.
Can you tell us which type of electronic ignition you have fitted please .There a great number on the market.
Bob

[davidmiles]

thanks Bob, I can't tell you what model it is, I don't have the packaging any longer, Ive ordered a new coil,rotor arm, spark plugs and leads, they should arrive tommorrow, I'll fit them and see if it starts, I have no idea how to test this electrical distributer to see if it is the item causing the fail.

[bmcecosse]

This is the problem with leccy ignition. When it fails - hard to find the cause. It could be the rotor arm - maybe tracking we can't see in that picture. Oh, and it's NEVER the coil..........

[davidmiles]

I've removed the spark plug from the 2nd cylinder from the front just to see if it's causing a problem by being heavily coked up.[frame][/frame]

[bmcecosse]

Well - it's NOT heavily coked up......

[davidmiles]

when I turned on the ignition switch and placed the positive probe from my multi meter on the metal connector of the coil and the earth probe onto the block, I got 4 volts showing on the meter.But an ohms test on the coil gave a 1, very low resistance.

[mogbob]

David
Checking it out from your photo, I believe you have an Accuspark ignition system fitted.
Their website is http://www.accuspark.co.uk it has pictures, so you can confirm, or otherwise, it's what you have.
The website has a Help section, info on their returns policy, bits about Ebay purchases, etc.

I always fix my negative lead to the negative battery post when checking out battery voltage supply but it's a personal thing.
You need battery voltage ( circa 12.6 volts, healthy battery) on the low voltage side supplying power to the coil ( White wire ) and from the coil to distributor ( white/ black tracer ).Ignition needs to be ON but switch it OFF, immediately after you have done the test with your multi meter.

Warning remember Roy's law.. it's never the coil !
Coil tests.Ignition off, leads disconnected ( mark/ note / take photo ).Meter on Ohms setting , red lead to + terminal, black lead to - terminal.Ohms reading on the Primary circuit should be around , some books say 2 Ohms, others say 3- 3.5 Ohms for a Lucas 12v coil ( non ballasted ).
To check the Secondary circuit ( disconnected as before ) Meter on Ohms...red lead to the + terminal, black lead to the central terminal, where the HT lead ( coil to distributor cap ) emerges from. A reading of around 5 Ohms is typical.
Re-connect leads correctly.

My money is on the rotor arm,marking the wise one's words ( Roy's ) but time will tell.
If the other plugs are as black then you might want to weaken the mixture slightly on the carb.Turn the nut , clockwise, viewed from below.
Bob

[bmcecosse]

Coil Primary definitely 3 to 3.5 ohms. The 2 ohm coil is for a ballasted ignition.

[mogbob]

Roy
Thanks for clarifying the" ballasted coil " 2 Ohms " norm " reading, it's always puzzled me.Appreciated.
Bob

[Alec]

Hello Bob,

although I've never measured it, I'm surprised at the figure of 5 ohms as the secondary winding has a huge number of turns compared to the primary and of a very fine conductor, I would've expected much higher?

Alec

[mogbob]

Alec
My source of info for that was Classic Car Electrical Systems Repair Manual Page 58
Bob