What is this on my intake pipe?

[Michael Burbidge]

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.

[BobTurner]

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.

[DaAV8R]

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

[Sam Buchanan]

Originally Posted by Michael Burbidge

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.

[randyintejas]

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.

[Michael Burbidge]

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

Thanks all
Michael

[gasman]

Originally Posted by randyintejas

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.

[chaskuss]

Originally Posted by Sam Buchanan

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

[Neal@F14]

Agree to just replace the intake tube rather than try to patch it.