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  #1  
Old 09-22-2012, 09:32 PM
Michael Burbidge Michael Burbidge is offline
 
Join Date: May 2006
Location: Sammamish, WA
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Default What is this on my intake pipe?

My O-320-D3G is used. It has some sort of probe on the intake pipe of cylinder number 3. Here's a picture of it. Do you know what this is? Maybe it was where they were taking the manifold pressure from. The primer port on cylinder number 3 had a plug in it. I'm now taking my manifold pressure from there per the Vans manifold pressure gauge instructions.



This is ugly and I'd like to remove it. How's the best way to plug it? I'm thinking of plugging it just like they have attached the probe.
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  #2  
Old 09-22-2012, 09:38 PM
BobTurner BobTurner is offline
 
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It looks like a port for an emergency vacuum system (need to run part-throttle so intake pressure is less than outside, then use the pressure difference as a vacuum source if your dry vacuum quit.) If my guess is right, you want to plug this up, otherwise that cylinder will always run leaner than the others.
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  #3  
Old 09-22-2012, 11:04 PM
DaAV8R DaAV8R is offline
 
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Location: Lee's Summit, MO
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Yep. That is part of the SVS standby vacuum system. As stated above, this provides an emergency vacuum source but did require less less than full throttle to provide 3.5" minimum pressure difference.

The part can be seen on the site listed below.

http://www.thevacsource.com/parts.php
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  #4  
Old 09-23-2012, 08:38 AM
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Sam Buchanan Sam Buchanan is online now
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Quote:
Originally Posted by Michael Burbidge View Post
My O-320-D3G is used. It has some sort of probe on the intake pipe of cylinder number 3. Here's a picture of it. Do you know what this is? Maybe it was where they were taking the manifold pressure from. The primer port on cylinder number 3 had a plug in it. I'm now taking my manifold pressure from there per the Vans manifold pressure gauge instructions.



This is ugly and I'd like to remove it. How's the best way to plug it? I'm thinking of plugging it just like they have attached the probe.
My first choice would be to replace that tube instead of trying to plug it. Second option would be to weld the hole.
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  #5  
Old 09-23-2012, 01:35 PM
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randyintejas randyintejas is offline
 
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Yep, TIG it up.. That is why I keep my TIG Welder around and for all the little Opps in the build process

Edit.. I would put a steel backer in there before I weld that so the material stays flush and does not dip down into the air stream.
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Last edited by randyintejas : 09-23-2012 at 01:42 PM.
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  #6  
Old 09-24-2012, 12:33 AM
Michael Burbidge Michael Burbidge is offline
 
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Default Replacing it...

I think I'll just replace it. I don't TIG weld. I can get one from aero stock for $64.

Thanks all
Michael
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  #7  
Old 09-24-2012, 01:54 AM
gasman gasman is offline
 
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Location: Sonoma County
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Quote:
Originally Posted by randyintejas View Post
Yep, TIG it up.. That is why I keep my TIG Welder around and for all the little Opps in the build process

Edit.. I would put a steel backer in there before I weld that so the material stays flush and does not dip down into the air stream.
Brass would work better as a back-up..... Finished plug would be flush inside and outside.
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  #8  
Old 09-24-2012, 06:00 PM
chaskuss chaskuss is offline
 
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Quote:
Originally Posted by Sam Buchanan View Post
My first choice would be to replace that tube instead of trying to plug it. Second option would be to weld the hole.
Mike,
Email sent regarding a good used intake tube.
Charlie
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  #9  
Old 09-24-2012, 09:19 PM
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Neal@F14 Neal@F14 is offline
 
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Agree to just replace the intake tube rather than try to patch it.
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