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01-22-2020, 12:03 PM | #1 |
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Join Date: May 2010
Location: Coral Springs FL
Posts: 10,879
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What size power valve should I use?
I have a Holley 390 4 barrel 4160 carb. List #0-8007.
Standard 1940 3 speed transmission. No A/C. or any other amenities except vacuum wipers. 1953 Ford V-8 239 cubic in. stock engine. Vacuum reading at idle is 18. Jets are #49 What size power valve do you suggest? The stock Holly came with #51 jets and 6.5 power valve. However, I read that the recommended power valve should be obtained by dividing the vacuum reading at idle by 2. Is that true? Thanks. |
01-22-2020, 02:00 PM | #2 |
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Join Date: Oct 2015
Location: Socal
Posts: 794
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Re: What size power valve should I use?
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"if your divided number falls on an even number, you should select he next lowest power valve number" By "the book" you'd use a 9 for a power valve, which isn't available. A 9.5 might be a little aggressive. (Every time the vacuum drops to 9.5 Hg, it's going to open) You might like the engine more under load before the PV opens, so a lower numbered power valve like an 8.5 or 7.5. (hook up a vacuum gauge and see where the reading goes as you're driving) |
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