im new to holley carbs, and was wondering what does the power valve do and what are the symptoms of a blown power valve?

thanks

power valve opens at a set amount of vacuum to let extra fuel in the engine.

a blown power valve would basically dump unmetered fuel into the engine at all times.

Well, unmetered isn't exactly true. It would add an additional metered amount of fuel when not needed.

Right, the PV orifice is sized (actually it is screw in on some applications, so you can change the PV orifice)

thanks 57, couldn't spit out the words, lol.

I also wanted to add the wrong powervalve can add unwanted fuel and cause an over rich condition. I have seen that way to many times Big cam wrong pwr valve and it flutters open at idle

just cleaned up a little spot for clarification.