How do you tell if the "power valve" is bad??

Running a .30 over, 440. Has a 750 Holley DP. How can I tell if the power valve is bad?

They don't go bad as often as people say. How old is your Holley carb, btw? After 92 or something, they all had the check valves.

edit: to tell if it's bad, take it out, and suck on the large end. No, I'm not kidding. If you can move the sprung piece toward you, it's still good.

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They don't go bad as often as people say. How old is your Holley carb, btw? After 92 or something, they all had the check valves.

edit: to tell if it's bad, take it out, and suck on the large end. No, I'm not kidding. If you can move the sprung piece toward you, it's still good.

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Well, yeah, they do. Or at least they used to. I used to rebuild Holleys "moonlight" while I was at Miramar. I've been into at least a hundred. I'd be I've found at least 5 bad power valves RIGHT OUT OF A NEW KIT.

So far a sucking on the valve, you cannot tell if it's leaking, which is what causes the problem. Another thing that causes them to "be" bad is overtightening, which warps the thing

The BEST way to tell is that a previously tuned car simply will not idle, and the idle screws have little effect. When I was doing this moonlight rebuilding, I used to mark and save valves that I knew had been OK on idle. The acid test is simple. replace with a a good valve.