Holley Carb question

[hemi68charger]

I have a friend with a question I can't answer right now.. What are the circled orifices used for?...

[John_Kunkel]

The one on the left is the manifold vacuum port that feeds the power valve chamber in the main body, there is an identical one at the rear and the brass inserts are check valves that protect the power valve diaphram in the event of a backfire.

The one on the right is a plug that blocks the idle feed channel when rear idle mixture screws are used.

[hemi68charger]

Thanks John..

All those make sense now that it's been explained.......

Cheers,
Troy