Thread: wont idle all of a sudden

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what is the purpose of the power valve? how do you know if its bad? im not sure

Originally Posted by S19243H

what is the purpose of the power valve? how do you know if its bad? im not sure

The power valve is simply a "switch" that opens at a predetermined manifold vacuum, measured in inches of mercury (Hg). A vacuum passage in the throttle body transmits manifold vacuum to a chamber in the main body. When manifold vacuum drops, a spring opens a power valve in this chamber to admit extra fuel. This fuel flows through the power valve, through the power-valve channel restriction and into the main well. There it joins the fuel flow in the main metering system to enrich the mixture.
If the power valve is blown it can result in a very rich condition at idle.
Most of this information came from the Holley Carburetir Handbook by Mike Urich. If you're going to work on a Holley I highly suggest you get a copy of this book or one like it.

This is the book I'm refering to.