Coil

[Carba1984]

Hello guys, I have a Spitfire 1500 from 1979 and I would like to know if the coil is ballasted or not, I want to change the entire ignition system. How can I know? Thank you!

[johny]

Right with some basic electrical knowledge its easy to test exactly what youve got. Connect a wire from your coil -ve terminal (its the side that connects to the distributor and make sure you have the correct one) to earth. Now measure the voltage to earth at the coil +ve terminal with the ignition turned on - dont leave the ignition on too long!

Approximate readings: 

12v = non ballast system but check coil resistance (see below).

6v = ballast system with ballast coil, correct.

9v = ballast system with non ballast coil, incorrect.

If you have measured around 12v its a non ballast system but you still have to confirm that you have the right coil for it by measuring its resistance. With the ignition off measure the resistance across the +ve and -ve terminals of the coil. A non ballast coil is 3ohms and a ballast one 1,5ohms....

 

[Carba1984]

Ok Johny i’ll try 

[Carba1984]

And if I’ll do This?
Remove all wires, set your voltmeter to Ohms.
A reading of around 1.5 ohms indicates a Ballast coil. A reading of around 3 ohms indicates a Standard coil.

[johny]

Thats correct but of course the wiring of the car has to be different to work with each type of coil and it might have been changed since its manufacture. My test procedure will also tell you which type of wiring you have... 

[dougbgt6]

I think a 79 had a ballasted system with a resistive wire instead of a resistor? The wire will be dull white with an indistinct pink strip. Sometimes they run to the coil, but sometimes to the starter solenoid. Another great Triumph idea to run a resistive wire through the loom keeping it warm! 

Doug

Edited November 14 by dougbgt6

[Carba1984]

Hace 1 hora, dougbgt6 dijo:

¿Creo que un 79 tenía un sistema de lastre con un cable resistivo en lugar de una resistencia? El cable será blanco oporto con una tira rosa indistinta. A veces corren a la bobina, pero a veces al solenoide de arranque. ¡Otra gran idea de Triumph para pasar un cable resistivo a través del telar manteniéndolo caliente!

Doug

I don't understand well, but I wanted to know if I buy a coil without ballast I can use it in a wiring with ballast?

[johny]

No, a coil for non ballast will be 3ohms and cannot be used with ballast wiring. For ballast wiring you need a 1,5ohm coil.

[Carba1984]

But,can you bypass the ballast cable? A friend has mounted the Lucas DLB105 coil (he says it's the best) and it's without ballast

[johny]

You can bypass the ballast and use a 3 ohm coil. Its easy if you have a separate resistor (earlier cars) but yours is probably a resistance wire that is hidden in the main cable. In this case you need to install a new wire from the ignition switch to supply the new coil...

[dougbgt6]

Find the white and pink wire, disconnect at the coil end and the ignition switch, run a new cable from the ignition to the coil. You may find the white & pink gets to the coil via a connection on the starter solenoid.

Doug

[Carba1984]

[Carba1984]

I am convinced that there is a problem with the coil and the distributor, the car has to be at more than 20 degrees BTDC for it to work properly and consequently the idle of the carburetters goes crazy, that's why I need to change the ignition but I'm very useless in electricity.

I still don't know what to buy, I've looked at accuspark which is quite cheap but a friend tells me to put the Lucas DLB 105 coil and a programmable 123 distributor but it's more expensive.

Right now the one I have assembled is electronic

[Pete Lewis]

back to basics  in the pic of the coil wiring there are 4 wires connected 

red black   where do they go ?    2 dirty whites   connected opposing ends of the coil  that cant be right 

on will be started 12v bypass and one a ballast ign feed   cant be on the pos and neg terminals  just the pos.+

Pete

[johny]

No, its alright Pete, black white on -ve which is correct to dizzy and white yellow on +ve from resistance wire/starter solenoid junction. The red and black wires go off to the electronic ignition but as seems to be common this means the electronic ignition is being supplied with 6v instead of the recommended 12v.

Carba if your coil is not 3 ohmns get one that is. Then find a white wire on your ignition switch or fuse box and connect another white wire to it to supply the +ve terminal of your coil. All the other wires on your coil stay the same except the white yellow one which must be disconnected. 

[Carba1984]

It's clear that I have a ballast installation, right?

[johny]

It certainly looks like it but not guaranteed without testing - in 40 years anything could have been done!

[dougbgt6]

Carba,

Do you have a mustimeter? Cheap as chips, resistance and voltage easy to measure, £10 or less on Ebay.

Doug

[Carba1984]

1 hour ago, johny said:

It certainly looks like it but not guaranteed without testing - in 40 years anything could have been done!

I’ll check 

[Carba1984]

1 hour ago, dougbgt6 said:

Carba,

Do you have a mustimeter? Cheap as chips, resistance and voltage easy to measure, £10 or less on Ebay.

Doug

Yes of course

Edited November 15 by Carba1984

[Carba1984]

Now I have an electronic ignition mounted and I can assure you that it is not mounted like that.

The red and black of the coil go directly to the distributor, I think I remember

[johny]

Thats it, your red wire goes to the coil +ve terminal after the resistor not before as in the diagram. This means your electronic ignition inside the distributor is supplied with 6v not the 12v it should have☹️

Can you see that if you want to use a 3ohm coil you have to bypass the resistor and supply the +ve terminal directly from the 'live feed' in the diagram...

[Carba1984]

23 hours ago, johny said:

Right with some basic electrical knowledge its easy to test exactly what youve got. Connect a wire from your coil -ve terminal (its the side that connects to the distributor and make sure you have the correct one) to earth. Now measure the voltage to earth at the coil +ve terminal with the ignition turned on - dont leave the ignition on too long!

Approximate readings: 

12v = non ballast system but check coil resistance (see below).

6v = ballast system with ballast coil, correct.

9v = ballast system with non ballast coil, incorrect.

If you have measured around 12v its a non ballast system but you still have to confirm that you have the right coil for it by measuring its resistance. With the ignition off measure the resistance across the +ve and -ve terminals of the coil. A non ballast coil is 3ohms and a ballast one 1,5ohms....

 

I'm making a lot of trouble in my head, I think I'm going to go step by step, first I'm going to check this, I'll keep you informed, thank you very much

[johny]

Good, I think its better to have a complete non ballast system (with Spanish weather you dont need ballast) so the electronic ignition has 12v. It might not improve things but at least you will know its correct👍

[Carba1984]

11 minutes ago, johny said:

Good, I think its better to have a complete non ballast system (with Spanish weather you dont need ballast) so the electronic ignition has 12v. It might not improve things but at least you will know its correct👍

Then the best thing will be to buy the coil without ballast, Lucas DLB105 and Maybe 123 distribuitor