Fiat Dino Forum (FDF)

Does anyone understand why there are 2 hoses that go from the intake to the air filter housing?
Greg A.

I believe there are 2 hoses that go from the crankcase to the air cleaner housing to burn off crankcase fumes.

Alex

On my car. Early 67. There are 2 small hoses that go from the intake manifold to the air filter housing. I'll take a pic tonight.

The question was why ? There are 2 hosens, one in the front and one on the last intake of the carburetors. The middel one has a small short circuit between the 2 barrels - I am guessing it does the same as the hose. But I dont undestand the purpose either ?

Greg,

I took a closer look and I believe that the 2 small hoses are Ferrari only items in use. I think they are run to the air box only for convenience in the Fiat. In the Ferrari motor I believe that they are part of the "Crankcase Gases and Oil Fumes Ventilation System".

The Crankcase is vented differently in the Ferrari and fumes are run directly to the intake manifold or perhaps the vacuum from the intake runners controls the pressure limiting valve.

If you find out for sure, please advise.


Cheers


Alex

I did some reading on this subject.
It turns out that the 2 small hoses are there i create vacuum in the air filter box when the engine is running with throttles are closed (idling).

With the throttles closed there is no suction to take the fumes from the crankcase. Therefore the 2 small hoses create vacuums in the air filter box, insuring the crane case fumes are feed back to the engine. Then the throttles are open the vacuums runs thought the carburetors and the not the 2 small hoses.
Regards Jesper

Thanks for the response. That's interesting.
Greg

Has anyone plugged the small hoses. And just vented the crankcase gasses to open air?