Hi folks. I have a 1978 Fiat Spider 124. It is parked at my dad's ranch, which is about a two hour drive from my house. I'm trying to get it up and running again so I can see about bringing it home to start restoring it.

I've had it running a few times over the past several years, but each time it runs maybe 10-15 minutes and then the ignition coil fails. So far I've been putting in cheap coils from the local Autozone or Oreilly. I haven't wanted to spend the money for a genuine Marelli coil until I can figure out what the underlying problem is. (But, maybe that IS the underlying problem?)

The most recent time I tried to start it, I used a cheap Autozone coil. I had 12V at the coil with points closed (dropping off to 8 or 9 volts when cranking). No spark generated at all.

The time before that I had an old coil off of an old Ford farm trunk my dad had at the ranch. That time the Fiat started up and purred like a kitten for about 15 minutes until the coil sprang a leak and all the oil boiled out (I think I nicked it pulling it off the truck).

I've had at least 3 coils in it before this that have either not worked at all, or have run for 10-15 minutes and failed.

The parts stores sell two coils - one WITH and one WITHOUT an internal resistor. I'm never sure which one to purchase, and I think I've tried both. I've attached a picture that shows a small cylinder that attaches to the coil. I'm not sure if this is an external resistor, or just some sort of RF filter for the radio.

Any hints would be greatly appreciated.

Steve

Never heard of a coil with an internal resistor. Some manufacturers used a 9 volt coil with an external resistor as a starting aid, but I don't think the Spider ever used that system.

The 2 types of coils available for the Spider are 1 for points ignition and 1 for electronic ignition. The difference is the resistance of the internal coil windings.

Points coil resistances: Primary; 2.59Ω - 2.95Ω. Secondary: 6750Ω - 8500Ω.
Electronic coil resistances: Primary 0.75Ω - 0.81Ω. Secondary; 10,000Ω - 11,000Ω.

If you were using an electronic coil on a points ignition system it could cause problems with the points burning prematurely.

Any 12 volt coil from a points ignition system should work, however you can probably source an equivalent for Magneti Marelli BES200A or Martinetti G37SU. These are 2 alternative manufacturers for the Spider points ignition coil with similar internal resistances as shown in the workshop manual page below.

The small cylinder attached to the coil bracket in your picture looks like a radio suppressor.
.

The points type coil has a built in resistor to reduce the voltage to the points to 9 volts. You need to replace the coil with a balasted coil. If the car still will not start then you need to check to make sure the points are not pitted and maybe change the condenser in case it is burnt out from trying to run the wrong coil. The cylinder on the side of the coil is a condenser to keep ignition noise out of the radio. Hope this helps.

I have an original coil from a 78 spider that would do nicely if interested.

I agree with everything Davren has said. I've never encountered a ballasted ignition coil fitted to the Fiat 124 Coupe/Spider and I worked for a Fiat main dealer back in the day! The brick red coloured block with 2 terminals (8mm nuts) if fitted, is a pickup to send a signal to the revcounter(tachometer) and is not iirc a resistor. Any small cylindrical canister with one lead only is a radio interference suppressor, as already said above. If you still have the original coil perhaps you can get a part number from it and cross-reference it to obtain a suitable replacement locally?
Remove the distributor cap, if contact breaker points are fitted, use the points type coil, if no points just some sort of inductive? pick-up fitted use the coil for electronic ignition but use the 12volt version in both cases. Be careful getting a coil from another car of the same age as iirc electronic ignition was an option for a while before becoming standard fitment so you could still end up with the wrong coil, also you don't? know what changes were made by previous owners/mechanics!
Al.