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Author Topic: Fox 35 venturi size  (Read 1229 times)

Offline Bill Hummel

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Fox 35 venturi size
« on: February 03, 2013, 08:14:58 AM »
Re-building a couple Fox 35's...if I use an ST NVA (.156 dia) how much do I open up the venturi to accomodate the larger NVA?  Thanks for any help with this...
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Offline RandySmith

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Re: Fox 35 venturi size
« Reply #1 on: February 03, 2013, 09:46:14 AM »
You would be better off using the proper size spray bar, either a Fox, SS PA type, or a OS 25.

Randy
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Offline don Burke

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Re: Fox 35 venturi size
« Reply #2 on: February 03, 2013, 12:13:58 PM »
Quote from: Bill Hummel on February 03, 2013, 08:14:58 AM
Re-building a couple Fox 35's...if I use an ST NVA (.156 dia) how much do I open up the venturi to accomodate the larger NVA?  Thanks for any help with this...
What's the stock venturi dia and NVA dia?
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don Burke AMA 843
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Offline Bill Hummel

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Re: Fox 35 venturi size
« Reply #3 on: February 03, 2013, 01:08:52 PM »
OK, thanks, Randy, that's probably the best way to go.  Don, the stock venturi opening is about .270, and the Fox NVA is about a .125. 
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Offline Jim Thomerson

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Re: Fox 35 venturi size
« Reply #4 on: February 03, 2013, 03:09:34 PM »
Many years ago, I switched my Fox stunt 35s to ST NVAs.  I intended to hog out the venturis but never got around to it.  The first time I met Alan Brickhaus, he told me the size I needed to open the venture to.  As said, i never got around to it, as my Fox stunt 35s were running to suit me.  I was twice asked by another contestant if I was running an ST 46.  :o My present Fox stunt 35 has had the squishband head replaced with a stock head, because it was too powerful. I run 11 x 5 props on my Foxes with 10% nitro fuel. 
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Offline BillLee

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Re: Fox 35 venturi size
« Reply #5 on: February 03, 2013, 03:32:24 PM »
Using the venturi area calculator on the NCLRA website http://www.nclra.org/Programs/Venturi.php I found that in order to get the same effective area using a .155" diameter needle valve, you need to open the venturi to just a hair under .295"
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Bill Lee
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Offline Bill Little

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Re: Fox 35 venturi size
« Reply #6 on: February 03, 2013, 05:29:51 PM »
In the case of a Fox .35 I would never use anything other than a stainless steel PA NVA from Randy.  It is necked down in the middle like a stock one and works much better than anything else out there.

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Offline Balsa Butcher

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Re: Fox 35 venturi size
« Reply #7 on: February 03, 2013, 06:53:31 PM »
Like Jim, I have never had any issues with running ST NVs with the stock venturi opening. That being said, My best Foxes use PA NVs. Stock spray bar thickness with fine adjustment and a better seal. The way to go.  8)
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Offline Bill Hummel

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Re: Fox 35 venturi size
« Reply #8 on: February 05, 2013, 04:48:59 AM »
OK, thanks, guys, all good info!
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