Runs rough after rain.

[alfapop]

Everything replaced in ignition system (plugs, wires, coil, condensers, points) except cap and rotor. Runs great except after a rain storm. I suspected a cracked distributor cap and was going to purchase one but when I looked at my current one I noticed two small holes in the back that look like they are supposed to be there. That doesn't make sense to me. They would let in more moisture than a crack! So maybe it isn't the distributor? The cap says Bobina on it. The best picture I can find on the internet can be seen at the address below. Can anyone provide some insight to this? If the cap is good, why is the car bucking after a rain? (Note after driving for a bit and heating the car up the bucking stops.

https://www.ricambio.co.uk/distributor- ... anchi-a112

https://www.ricambio.co.uk/distributor- ... anchi-a112

**Late post - I just noticed the two green wires running from the coil to the points have been spliced at some point and the electrical tape on them is very brittle. So I suspect moisture would easily get to the splice. Is this the likely source of the problem?

Thanks,
Rob

[18Fiatsandcounting]

Rob, moisture in the wrong places can definitely cause misfires and rough running, and it's usually an ignition problem. The cap and rotor are especially problematic, and those are the two parts that you didn't replace.

But, before getting new ones, try given them a good cleaning with soap and water, carb cleaner, brake cleaner, whatever you have. Residual grease and dirt on the inner contacts can lead to the spark "grounding out" before it ever reaches the spark plug, so get it as clean as you can. By the way, if the gap on the spark plugs is too large, the current will find an easier path to ground, and that could be through faulty plug wire insulation or connectors, dirty spark plug exteriors, dirty coil, etc. Check those too.

Bobina is an original style cap, and my recollection is that the two small holes are as designed.

-Bryan

[alfapop]

Thanks. I think I will replace the cap and rotor anyway - not that expensive. I didn't in the beginning as I couldn't find the cap in stock anywhere but can now on several sites. Will fix the splices as well as clean things up as suggested. Can't imagine doing those things won't do the trick. Factory holes in the distributor cap . . . who'd a thought?

[18Fiatsandcounting]

Factory holes in the distributor cap . . . who'd a thought?

Total guesswork on my part, but since sparks produce ozone and ozone is corrosive, maybe the holes are there as vents so ozone doesn't build up inside the cap? How's that for some serious hand-waving?!

-Bryan

[PaulC]

Bobina is not a brand name but is Italian for coil which is the terminal for the coil cable.

[18Fiatsandcounting]

Bobina is not a brand name but is Italian for coil which is the terminal for the coil cable.

Thanks Paul, I did not know that! Makes sense, as an ignition coil is a kind of bobbin (wire instead of thread), and so I guess all my distributor caps that have "Bobina" on the top are just marking the terminal that goes to the coil.

Learn something new every day!
-Bryan