Technical Ignition Coil Wiring

[MauroV]

Hello

I am currently converting my 1965 Vauxhall Viva from positive earth to negative earth and so I checked on my 1970 Fiat 500, which is of course negative earth, to make sure that the new Viva wiring matched the Fiat. However, now I'm confused. On my Fiat, the dark green/dark blue wires attached to the positive terminal on the coil go to a resister and to the distributor while the light green wire from the harness and presumably coming from the ignition goes to the negative terminal. From my research, on a negative earth car, the positive terminal should be attached to the ignition.

So please can someone put me out of my misery and let me know how the ignition coil on a 1970 Fiat 500 should be wired.

Thanks

Mauro

 

[MauroV]

The reason I am worried about this is that I have a warm start problem with the car and I heard that this can be affected by the ignition coil health. I put a new coil in and was careful to wire it up as previously, with the ignition feed to the -ve side, but it made no difference to the warm start. Now I see that it is more usual to have the ignition feed to the +ve terminal on the coil and if its the wrong way round you can get a weaker spark so perhaps that is my problem.

I looked at another Fiat 500 coil this morning. That one had the live feed from the ignition attached to the +ve terminal and the -ve terminal attached to the distributor. But it wasn't exactly like mine in that it had no capacitor connected to either side if the coil, see the photo of mine.

So does anyone have the same set up as me with a capacitor running from one side of the coil to earth?

If I swop the live feed to the coil from the -ve terminal to the +ve terminal, what should I do with this capacitor, leave it attached to the +ve and so directly connected to the live feed (and then directly to earth) or move it with the wire that connects to the distributor onto the -ve terminal?

Many thanks for your help.

 

[fiat500]

If I swop the live feed to the coil from the -ve terminal to the +ve terminal, what should I do with this capacitor, leave it attached to the +ve and so directly connected to the live feed (and then directly to earth) or move it with the wire that connects to the distributor onto the -ve terminal?
/QUOTE]
MauroV.....DO put the live feed to the positive terminal on the coil and either remove the suppressor or leave it it on the positive side.

But check that someone hasn't somehow reversed the battery terminal and made the car positive earth. That's very unlikely because the original positions and lengths of the battery cables normally makes this impossible.

 

[MauroV]

Hi Peter

Thanks for your reply. So, it's a suppressor, presumably for a radio? I don't have a radio so I can just remove the suppressor and switch the cables over?

That sounds like a brilliant plan.

Mauro

 

[fiat500]

Hi Peter
So, it's a suppressor, presumably for a radio?

It seems likely; I can see the condenser on the side of the distributor, so you should be good to go by removing the suppressor at the coil.

 

[MauroV]

Thanks Peter I'll give it a try. What you are saying makes a lot of sense. I really appreciate your help.

Mauro

 

[MauroV]

I changes the wires over and disconnected the suppressor. Everything seems fine, not having the suppressor hasn't made a difference. But what is different is the warm start. Its perfect now. It's still very hot here in Italy and the car really roars into life, in situations when I know I would have struggled before.

 

[the hobbler]

Morning Mauro;
Is that a real Giannini, or a replica? I have a replica Abarth 695 and whilst I am a huge fan of Abarth, I would be the first to admit that Giannini was a very fine tuner of the Cinquecentos, and in some ways better than Abarth---they got the same amount of power out of, very often, a slightly smaller engine.

 

[MauroV]

Hi Tom

Nice to hear from you. The car is a kit Giannini, modified back in the day but not modified by Giannini themselves. It is identical to a 'factory' Giannini 500TV with all the right badges, chrome and wheel covers and is listed as a Giannini by the Fiat 500 Club Italy but is really just a very good replica. And as you know, the engine is a 650 with a dellorto carb which isn't very authentic although it does say Giannini on the sump.

Cheers

Mauro

 

[the hobbler]

Nothing wrong with it being a 'replica' Mauro, in fact it often makes for a better car as the parts are likely to be newer. Genuine Giannin's are close to 40 years old (genuine Abarth are AT LEAST 50 years old, delicate and EXPENSIVE). My own car is a replica 'Abarth 695' (based on a 1972 500L) and I have no hang-ups about that at all. If you let me have your e-mail address (mine is:- [email protected]) I will send you some pictures of it---attracts a lot of visitors at shows.