CRG Discussion Forum
Camaro Research Group Discussion => General Discussion => Topic started by: wisemanz28 on April 22, 2022, 12:09:38 AM
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Trying to figure out my power valve size. Wanted to share the pics and get the groups opinion. The first pic is the primary side, second pic is the secondary side
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Knowing what power valve you have is as easy as reading numbers. The face of this power valve has the numbers 8 and 5 on it. That means that this valve opens at 8.5 inches of vacuum.
Reference: Link
https://www.racingjunk.com/news/choosing-the-right-power-valve-for-your-holley-carburetor/
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8.5
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I also am seeing a number 6, I just wanted to be sure.
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If you need a couple of 8.5" new Holley power valves, send me a PM.
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First picture of the primary metering block has a 65, second picture of secondary block has a 85.
You read the numbers on the right hand side, the left side with the aplha numerical digit with a number underneath it is not a identifying number. You can also tell the higher value power valve by the effort it takes to push the other side of the valve although the difference between 65 & 85 is negligible.
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We've been using 6.5s with our restos. They seem to work better for the street.
Jerry
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Have you considered plugging the secondaries' power valve opening, gone down 1 step in the the vacuum spring and increased the secondary jetting to 84-86?
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Have you considered plugging the secondaries' power valve opening, gone down 1 step in the the vacuum spring and increased the secondary jetting to 84-86?
Nope, don't do that.
FWIW, start out with the stock specs, eg: jetting (68/76), power valves, springs etc. Then IF needed, move up or down. When running, use a vacuum gauge. This will get your tuning spot on for a correct power valve. Also, make sure you do not have any vacuum leaks from cracked hoses, lines, gaskets, etc.
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A good baseline is 72-76s. That is standard jetting in the 3310 Holley carb. If you're blocking the rear power valve, then add 4 to the rear jetting making it 80s in the rear.
Jerry
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Do you stagger jet your 4053?
Do you use the bigger accelerator pump?
What size nozzles do you run?
paul