I'm seeing a lot about electric vacuum pumps. How do they work? Is there a main vacuum source that the pump attaches to and then attach to delivery hoses?

 

The pump creates the vacuum, it does not have an external source.
Is your engine highly modified that you are considering this?

 

Not really, just looking ahead if I have vacuum issues, and want to educate myself on how they work. I guess that you plug the vacuum t port behind the carb and tie the hoses coming off the tee into the electric pump?

 

I have to add one to my car and am mapping out what I am going to do.

I only really need it cause i have less that 16" of vacuum and a 7" brake booster so its not enough to keep my brakes assisted correctly under all conditions. All the other vacuum stuff works fine on 16"

Turbo cars are very common to have them now. I bought a Leeds black bandit as I like the quietness of the rotary vane pump over the piston style .
You cannot just add this to the back of the carb port as all you will do is suck from the engine and it will never shut off and it wont help you. You need to plumb this in with one way check valves to prevent leak down.

Most guys just divorce the engine vacuum completely from the brakes but I have been doing some planning and am going to add a late model hose setup to my booster so that I have some redundancy like the newer turbo cars do it today.

I like the leeds pump but will also be changing the relay wiring from a one wire setup to a 12v dedicated design so it runs like a motor on a relay should.

Below is a 2016 chevy cruze with turbo hose that use the exact same pump that the leeds pump contains. This hose has all kinds of one way valves in it to prevent the leak down I was talking about and provide the redundancy of engine vacuum plus the pump without either one affecting the other.