9a 16v timing advancing?

Hi all,
I have a 9a engine including the ecu and tci in my mk1 running on carbs  but I'm not sure if the timing is advancing or not. I presume the ecu provides this? But what provides feedback to the ecu so it knows to advance? Is there a way I could check it's advancing?
Thanks
Keith

ecu adjusts advance based on hall sensor input, coolant temp and vacuum from the inlet

Many thanks John,
I have achieved a lot with this car as a direct result of the information you give freely on this forum. I hope I can help others when I come out the other side of this project.
Best regards
Keith