i have a holley model 6210 quadrajet type carb and it has a plug called the gulp valve. right now it is plugged. can i used this as a vacuum source for my power brake hose.

 

As long as it has an opening that's been drilled all the way through the base of the carb, then yes you can. Are there threads there for you to screw a nipple into, or are you going to need to thread it? Don't you have a vacuum fitting at the rear of the intake manifold?

 

the carb has a fitting that fits a 5/8 hose. i can remove the plug with a screw driver. the reason i need to use this fitting is because the carb is a double pump and the secondary mech pump lies over any fitting i install on the intake manifold. it is that close. the opening of the fitting extend out to the opening of the intake manifold. so i guess it gets full manifold vacuum and not any gas/air mixture.