Morris Minor Owners Club

Having got my 57 convertible going I have noticed that the engine is a hell of a lot quieter and smoother than my 61 which has a 1098cc fitted. I know the 948cc is meant to be a smoother engine but I've got a video of the 1098cc anyway and I've noticed (hard to tell in video) that every now and then it has a sort of miss, I was thinking maybe timing needs tweaking slightly but what do you think??
https://www.youtube.com/watch?v=EWJBh37CUWA

The 948 engines are smoother. My own 1098 has that 'idle miss' - I've never been able to eliminate it.... Maybe it's the coil?