Upgrade a 401 heating system?

[Geoff Kingston]

Hi Dave,
I had seen something about this a while back so having seen your advice I looked up the relevant section in the 401 handbook and explains the reason why this works and how vents open windows shut creates a slight cabin pressure which is useful apparently if you want to keep dust out of the car when driving on dusty roads but not if you want heating or to recycle or as they put it in the handbook recondition the air inside the car.
The only reason I was thinking about possible changes was that I remember someone years ago telling me they had changed the system on a customers car. This might have been to allow blower assisted air into the cabin as well as for demisting. I will have to take everything apart as the water hoses are perished and the heat exchangers and valve have not had any water in them for over 40 years so I will probably have the exchangers reconditioned when I have the main radiator I intend to use done. I might just put it all back and see how it works, its so long since I used a 401 in the winter that i really could not remember if the system was good or bad, I do remember a heat exchanger bursting on a 401 once that was quite spectacular and it was a good job the carpets were old and there was no passenger on board at the time.
Thanks for you help.
Regards,
Geoff.