Hello.
I've got an old fiat x1/9 1500 (1980) . Back in the early 80's the engine was blown and a replacement fiat ritmo 85S engine was installed. I spoke with an earlier owner, who told me the head was taken from the x1/9 and mounted on the ritmo engine because it was a bit "hotter". I've had a look at the engine and can see that it's not an original cam but an aftermarked cam .. but how can i find out what type cam it is ?.. does anyone know how the find out? should it be marked in a special way...and where? Plese give me som advice if you maybe know.

The fiat part numbers are usually marked between the lobes. If it's after market then it might be in the same place or on the pulley?

The previous owner probably meant that the x1/9 cam and head was hotter than the ritmo? But its possible its something else. The x1/9 had the hottest fiat cam of all the 128 variants.

If it's a mainstream aftermarket cam it'll be stamped on the left end of the cam. There is a cover held on by 3 10mm bolts, take it off and let us know what you see.
Mine is a piper fast road cam and the markings are here. Faza and pbs did the same.