Holley Power Valve Experimentation

RustyRatRod said

Ok so the spring rate goes up as the vacuum opening increases. I wonder if stretching the spring just a little would do it? Crude, I know. You can get a power valve tester to see.

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I’m looking at the Moroso tester, trying to sift through the reviews to see if putting a specific vacuum on it will be accurate other than merely as a leak tester. Anyone have experience with one or from another brand or options for accurate measuring?