I do not even know where the air filter is located.
On the top of the cylinder head cover there is a
kind of silver metal "cap". On the front grille side
it's round, on top it's flat with huge letters "MORGAN",
on the windscreen side there is a short but quite large
tube, connected to a black "pot" which has a kind of
snorkel on it's side. Maybe the air filter is in there?
Unfortunalely I don't know how to post a picture here.
Thank you for your answers!