Fuel line purpose and size?

[Tduv]

I have some old fuel lines on my Tower of Power. Was wanting to replace them as they are old. I was just wondering what size you might think they are and what is their purpose? The little hoses in the pictures

 

[Tduv]

Vent tube sizes?

I was just wondering if anyone know the inside diameter on the vent hosing on a 1976 mercury 1150? My manual has not come yet and won't for a bit and can't find this info anywhere! Thank you

 

[GA_Boater]

In your 1st post, the little hoses are for oil recirculation to lube the crank bearings.

Pull one off to size the hose. A word of caution - those hoses and the fittings in the block become brittle and fragile over the years. I wouldn't mess with them unless they need replaced.

In your 2nd post, I'm assuming you're referring to the same hoses. "Vent hosing" is a puzzling term if you mean the same hoses as the 1st post.

BTW - the 2 threads have obviously been combined and re-titled the thread.

 

[Tduv]

Thank you for the response. Thoes lines are looking cracked so I was wanting to change them. I found out 3/32 inside diameter is what I would want. In the second post I was wondering what the thicker hoses were that the little ones connect to. The big hoses are Inline by the carbs but are not for them as they don't connect anywhere on the carbs. Hope that helps a bit Haha. Thank you again