600 with a 903 wiring question

dietzte

New Member
Hi, new member so apologies if this is the wrong place to post this:

I have 1966 Fiat 600(Argentinian) with a 1970 850 Spider 903cc engine; it has an alternator marked "Fiat" with three terminals, an electric fan, and a regular(non electronic) distributor. I am looking for the simplest way to connect all the engine compartment wiring(tail lights are bundled separately) with their proper relays as neatly and simply as possible. I have a two-pole Marelli regulator, along with a couple of relays(two after market and one OEM) that were connected "creatively". There is also a ceramic resistor on the firewall. I also want to add a fan relay switch connected to a sensor in the lower radiator hose(I have the parts).

I have seen lots of diagrams, but I'd really appreciate a simple description/diagram of how the wires should connect to the alternator, coil, and related relays. I realize this is a relatively simple problem, but I'm a newbie to Fiats.

Thanks in advance.
 
Here is a wiring diagram I made to install an 850 type alternator in a 600. You will need two Sipea 5230 relays (or equivalent). One relay cuts off the alternator field circuit so the battery doesn't drain down when engine isn't running. This relay can be mounted next to the regulator like in photo of my car. The other relay is for the no-charge light on the dash and can be mounted under the dash.
img011 (2).jpg


The easiest thing to do of course, is just retain the original 600 generator.

I have an electric fan in my 600 and just wired the fan motor through a thermostatic switch I installed on the radiator. A fan shouldn't draw that much current that it needs a relay.
 

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Thank you. I will look over the illustration and follow up.

Your installation looks terrific! Just what I had in mind.

Previous owner wanted an 850TC replica, with Abarth badges, oil pan, and valve cover(and wheels with small Abarth covers)...even put an Italian flag on the top of it and painting it red. I pulled the front radiator and pipes but probably won't add a lot; I know the guy who put front disc brakes and the engine in 20 years ago, so he's really helped me out with this, my first Fiat.
 

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Question about the upper diagram with the "x'd out" indicator light. I'm not sure how yours is wired in; I was able to trace its red wire back to the engine compartment, but it is not connected.

Also, I've never seen a coil mounted like yours--neat job--but what is sitting next to it(looks like a capacitor)? And how, if at all, does the fuse box play into this[I've seen some wires leading to the fuse box in a couple of different books]. I'm just looking for the simplest way to do it.
 
The coil is from either a late 124/131 with electronic ignition or he has a Plex distributor. Both use the same aluminum heat sink. The capacitor is for radio noise suppression.

I did have the same question about that part of the diagram as well.
 
Ok, thanks. While I can use an electronic setup that came with the car, I am--for now--using the original distributor/ignition. Same with the carburetor; I have a couple of options, but right now I have a simple, single barrel carb just to see how everything performs. This is my first Fiat 600, so I can make improvements as I go. Straightening out and simplifying previous owners' choices comes first. My friend, who installed the 903 years ago, can't remember what, if any, internal changes were made to the engine(such as camshaft). It is an Argentinian model, so there are some obvious differences between it and the Italian-made 600D.
 
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