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Sounds like it's sucking good. My stock 5.0 out of 91 Mustang pulled 18 inches at idle. It now pulls only 11 inches after I added numerous aftermarket items (cam, heads, ect).
 

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4402 does 17"
 

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Discussion Starter · #4 ·
Good stuff, thanks for the confirm, now I have to find a powervalve that is about a 15, I don't think I can find it.

This engine has head workand a cam, I guess it is pretty healthy.
 

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Aaron a 10.5 PV will work just fine for you. It's when you get into the lumpier cams that you have to get closer to the idle vacuum because you have so little vac signal to work with to begin with.
BTW - 17" is just fine - sounds like a pretty healthy engine. Did it burp well for you?
 

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Aaron,

Go lower on the PV as Randy suggests. You'll risk running rich at idle otherwise. You on the road?
 

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I've got around 5.5". Maybe a lumpy cam and 4800' elevation has something to do with that ;)
 

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Aaron, a 15 will be too big. I pulled this off the Holley website -

A stock engine, or one that is only mildly built for street use, will have high manifold vacuum at idle speeds. To determine the correct power valve the vehicle should be driven at various steady speeds and vacuum readings taken. The power valve selected should have an opening point about 2" Hg
below the lowest steady speed engine vacuum observed.

I have a 10.5 in my 750cfm for my 408ci. It has an idle vac of 17".

Hope this helps! Al
 

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boost pressure is in Bars 1 = 14.7 psig ....I think
 
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