Hi everybody!
After a major engine rebuild, my 68 T started to run weird after 4500 rpm.
The engine struggles to increase rpm - it increases, but not as expected.
At this point, the tachometer becomes crazy and shows more rpm than in reality - it goes to 8000 rpm. This is why I relate this issue with the distributor.
It feels like at around 4500 rpm, a vibration is produced and the sparks increase frequency or the spark timing slightly delays or advance... (???).

In case anyone ever experienced this, please share your thoughts.
Thanks.