Practically Classics Forum

had a few problems with the singer last sunday.
decided to change the coil, dizzy cap and rotor arm (easy huh)

Not a peep! no spark (slight one when switching the ignition off)

changed the coil, cap and rotor back to the old one..nothing still.

so, with the ignition switched on (some sort of electronic ignition fitted) I have about 11v across the coil..should that be a full 12v?
Checked everything I can think of, changed the ignition leads for another set..nothing.

only thing im not sure about is this little blighter that is next to the coil, linked to the - terminal..what is it and will this kill the ignition if its defunct..how important is the earthing to the body of it (bolted using the same bolt as the coil bracket)



Help!

Kev

I would guess that's a "condenser" for the radio (a capacitor under another name!) and should fail open-circuit, so shouldn't cause a problem. They earth through the can and are often bolted to the coil mounts.

Are you sure the points are fitted properly and not shorting out? That would explain the 11v across the coil too. If an annoying Scotsman in Spain can do it to a big Healey, I think you are allowed to do the same thing! It's an easy mistake to make (I confess to having done it in the past!).

Electronic ignition so no points to set.
Weirdly, just been in the garage to check a few things out (as one does when having issues such as these) and she fired up with no issues!
Gonna do 2 things tomorrow, remake all the connections to the coil (new connectors, soldered on) and get a new coil-dizzy cap ht lead.


hate cars me...lol

Kev

A capacitor is slightly more likely to fail short than open! PIO (Paper in oil) ones such as that suppressor are roughly 65% likely to fail short and 35% likely to fail open.
I'd bin that cap anyway since it's simply not essential where carbon string leads are used, where the aerial is well earthed and where the radio is mostly used on FM.

I only use my iphone playing music through the sony radio so doesnt matter about interference.
I will whip the item off tomorrow.

Kev

My memory was close, it's actually 67%.

This is the item in question



made by lucas if that helps

so, into garage early this morning. car is dead once again, so definitely something breaking down id say.
I have 12v to the coil but this drops to 10v when cranking!
if the ignition is left on, the coil warms up as expected but the lucas item above also heats up.
Blood annoying as I am totally out of my depth with ignition systems.

kev

interweb is a fantastic thing eh

the item in question is a ballast resistor

http://www.ebay.co.uk/itm/Lucas-Drive-R ... 4179433e2f

so, next question is what does it do and will this be a likely cause for my woes?
do i replace it or do i get a coil with built in ballast resistor?

kev

If you are using a 12v coil, I wouldn't expect you would use a ballast resistor as well. IIRC, the Minx I had didn't have a ballast resistor and used a 12v coil as standard fitting. There are two reasons for using the resistor - 1: to use a lower voltage coil (as I had in my Maxi when I had electronic ignition with a coil from the same firm - Mobelec - to "suit" the electronic system) or 2: to use where there is a separate feed from the "start" position on the ignition switch that feeds to the coil side of the resistor and, when in "run" the coil feed is via the ballast resistor to the coil. This is so that there is a bigger spark when starting the car - and the coil doesn't burn out while it is running! The feed from the ignition would normally go to one side of the ballast resistor and then from the resistor to the coil so that the coil drops voltage.

I was assuming that you have positive earth (and the coil negative terminal goes to the ignition switch, the positive to the "points"). However, I had either not realised or forgotten that it has electronic ignition (ie no points). If it has electronic ignition, is it negative earth too? If so, the positive terminal on the coil needs to be connected to the ignition switch.

I wonder if the electronic bit has died and isn't "opening". Testing it may be easy (I haven't had a lot of experience with modern units - having had diesels for 24 years!). One way of testing the rest of the system would be to put a plug lead into the coil's HT terminal and a plug in the lead (earthed to chassis) and, with a flying lead from the "points" terminal of the coil, flash the coil to earth and watch for a spark from the plug.

I'd expect 12V and 10v at the coil's switch terminal - working the starter motor will make the battery voltage drop by a volt of two.

John's probably right about the capacitor (of course he is right!) - I was thinking "electrolytic" when I saw a round capacitor with a lead from the end

Its a negative earth system.
I am considering removing the lucas item from the wiring system to see what happens. My thoughts are that the electronic side of the system has packed its bags though!

Kev