500 (Classic) 1968 fiat 500 running rough

[Timowen6]

Hello.
I have a 1968 fiat 500 and it’s running like it’s lacking power when accelerated. I’ve checked the fuel supply and all seems fine, engine was running great the last time I took it out.
The only thing I did do was put a none return valve on the fuel system recently and wondered if that was the problem. I’ve taken it off but still no better. But ran fine previously with this on.
One thing I have noticed is the fuel filter is only ever half full does it need to be above the carb ?
I’ve got a mate going to look at the carb at the weekend.
I was wondering if anyone here had any tips.
Thanks in advance.
Tim.

 

[BambinoClassic]

Hi Tim,
I had a similar problem with mine. In one instance, the lack of power was on initial acceleration, then it would pick up and be fine. In this case it was the idle jet on the carb that had gotten blocked. A clean out solved that one.

In the second instance, the lack in power was uniform throughout, and almost dangerous.
It happened to be the cap on the distributor was slightly out of alignment, causing issues with the rotor turning. I think that was a highly unusual occurrence but you never know.

I assume the points, valve clearance, timing and mixture are all tuned properly too?

Good luck!

 

[Timowen6]

Thanks very much. I will investigate these bits. Fingers crossed !