Carburetor Vacuum Ports

[hrosenthal]

I'm just curious what the vacuum ports are used for.
I've looked online and see many references to the ports, but none showing how they are used.

[Ray]

I'm just curious what the vacuum ports are used for.
I've looked online and see many references to the ports, but none showing how they are used.

Vacuum advance for distributors, vacuum feed for power brakes are two uses.

Ray

[edwardb]

There are two kinds of vacuum ports -- timed and full-time. Timed are above the throttle blades, and produce vacuum as the throttle is opened. Typically they are used for vacuum advance distributors. Full-time ports are below the throttle blades. These have vacuum at idle, but vacuum does change with throttle position. Full-time ports are used for things such as PCV and vacuum power brakes. It's extremely important that any unused ports are capped.