I think there are different philosophies and ideas out there.
Honestly i'm not a fan of oil feeded open roller bearing or plain bearing.
If i had to rebuildt my engine i allways would go with a vented tube (by holes) and a high quality sealed roller bearing.
To drill holes from the inside of the tube will be possible but will need a special driller and a very precision drilling to not harm anything outside the tube or the tube. Also there is a danger that drilled parts could get into the engine from the outer side of the tube while drilling. So no option for me.
Alternatively i think it's a good idea to seal the tube volume by a king of machined plug and use a sealed roller bearing. The question is what material to use. A soft aluminium alloy could be a good idea, because of a high thermal coefficient. If pressed in this could be a good air sealer directy behind the roller bearing.
Regards
Markus
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