General Still wondering ….

[Highland jamck]

…Where to aim with the recently acquired 500 that starts and runs reliably, mainly. I’ve parked the electrical issue for now as easily bypassed. On occasional short trips out, though, it runs fine mostly, but then coughs, or rather baulks, heavily, like there’s an intermittent fuel issue. Apart from once I’ve got home, but I fear that’s mainly because I’m going such short distances and I’m playing Russian roulette. Peter T wonders if ignition may be the problem and it’s something I’ll try to check, but I’m also wondering if water in the fuel is possible - anyone able to comment? I should probably have ditched the fuel in the tank, and might do tomorrow, as I have little idea how long most of it was there. Thanks for any consideration

 

[fiat500]

Definite progress much thanks to Peter @fiat500 … the red car has been on two small outings today and got all the way back both times without complaining. Seems like detailed improvements to spark distribution and adjusted valve clearances has made a real difference, and I’m learning some of it along the way .

What with the couple of electrical issues being parked or bypassed for now, I’m building up confidence. Who knows where it will end …. Nairn, maybe, still some way off ready for the NC500!

For the benefit of others chasing bad running problems, here's what we did.
Valve clearances surprised us by being too wide. On the one sampled it was more than 0.25mm. Someone may have set them for the later engine and/or at the wrong point in the engine cycle.
The top part of the carburettor at least, is not original Weber as it lacks the brass hex cover and filter. The mixture and idle needed a lot of tweaking to get smooth running.
The spark plugs were the protruding type for the later engines.
The points were cleaned and adjusted. Importantly, the tiny C-clip from the pivot post was missing, and this can cause them to jitter at speed
The non-original rotor arm had damaged the inside of the cap. This may have been after I adjusted a non standard bend in the over-long brass electrode. I fitted a used but genuine Marelli set.
More peripheral details came to light, where the previous owner has finished certain details incorrectly. The nearer we get to standard the better this little beauty will run.

 

[Toshi 975]

Interestingly I have a similar situation going on down here in the South. I saw a post on Facebook with a plea for help with a non running 500 here in my home town which is extremely rare. An enthusiastic younger man had bought a 500 about four years ago as he loved the idea of owning one. He had hardly been able to drive it and it had pretty much been a non runner for the last three years even though he had three different garages or mechanics work on the car. After a couple of visits and a selection of ignition parts the car burst into life and he was able to go for a drive, the smile on his face was a sight to behold.