1982 924 vacuum routing question

[awilson40]

I have another Tech question.
What is the purpose of the ' ventury tube' that goes between the intake (vacuum)
and boot after the fuel distributer.... It also 'y's off to the brake booster.
I have always seen the brake booster directly connected to the intake manifold to
get its vacuum source. I have had a hard time tracing out several vacuum leaks and found that if I plug this line
with the 'ventury tube' my idle drops right down.

[drew1]

awilson,

I'm interested in this , too, if it is that black plastic part. I wonder if some kind of check valve could be in it.

drew1