If you are talking about the hose on the top of inlet manifold then it could be used. You will need to place a PCV in between it and the crancase breather otherwise you may have tuning issues. A Corolla PCV-013 works well.

If the carby has a plastic port above the throttle butterfly then you can just attach a breater hose directly to it.

If you mean the hose with the bolt blanking it off? It was receiving air from the air pump when you lifted off the throttle, not from the breather.

Most minis with some kind of crankcase ventilation did put the fumes back into the inlet manifold but with some control like PCV valve, or feeding in before the carb's butterfly. If you connect a breather hose directly to the manifold it might affect the fuel mixture.

Follow "gtogreen1969" advice about connecting the breather. For example, the mini K simply had a short hose going from the rocker cover spout (which also had a small oil trap) to a spout on the air cleaner box.

Here is a clearer shot of what I have. You can see a small vacuum line in the inlet manifold and the carburettor, both blocked.
You can also see the crankcase breather going to the rocker cover, and the larger blocked lines on the carburettor and inlet manifold. So how should these be connected correctly?



Thanks

I would plug the rocker cover hose into the carby (remove the red plug)

Then plug the crankcase breather hose into an inline PCV and then to the inlet manifold fitting on top.

At the moment there is no crankcase breathing because both breathers are connected to each other.

I agree with gtogreen1969 regarding connecting the rocker cover hose to the brass pipe on the carburettor which has the red plug on it at the moment, which will allow crankcase pressure to be vented back into the engine.
I'm not quite sure what he means by plugging "the crankcase breather hose into an inline PCV".
Does he mean a PCV like this?
https://minikingdomonline.com.au/product/pcv-valve-new/

Can't ben23f just blank off the hose coming from the oil trap on the engine side plate and avoid the expense of a PCV?

This is the type of PCV i was thinking of. https://www.autobarn.com.au/fuelmiser-pcv-valve-sp05950

I wouldn't blank off the rear crankcase breather.

Awesome thanks for the info.
What about the vacuum lines?

Worth worrying about or leave them as is?

Which vacuum lines?
As I understand gtogreen's ideas:
1. Keep the hose coming from the engine side cover oil trap: disconnect the other end from the rocker cover; fit an inline PCV; connect this to the outlet on the manifold that has the short hose and blanking bolt.
2. Use a new hose to connect the rocker cover spout to the carburettor where the red cap is.

On the carburettor just up and to the right of the red capped line, there is a small black plugged line (about 3mm diameter).
Similarly on the inlet manifold near the bottom of the photo.

Just wondering if I need to do anything with these as well?

You would connect that one to the vacuum advance on the dizzy. If it has one.