Cliff's Quadrajet Parts and Rebuild Kits

General Category => Quadrajet Carb Talk and Tips => Topic started by: Marx3 on January 25, 2016, 03:39:55 AM

Title: What is the point of this?
Post by: Marx3 on January 25, 2016, 03:39:55 AM

I noticed this little fella, sticking out into the barrel on a 18087175, I am about to re-calibrate for a stock 403.
Is this some sort of Venturi vacuum source for the EGR?


(http://i1108.photobucket.com/albums/h408/151182/Mobile%20Uploads/C937FF82-3C23-4981-BE33-FA5EA3A3A462_zpsg5pp92gj.jpg) (http://s1108.photobucket.com/user/151182/media/Mobile%20Uploads/C937FF82-3C23-4981-BE33-FA5EA3A3A462_zpsg5pp92gj.jpg.html)

Title: Re: What is the point of this?
Post by: Cliff Ruggles on January 25, 2016, 04:24:53 AM

Never heard of or seen that carb number, or an extension on that bleed hole on a q-jet......Cliff

Title: Re: What is the point of this?
Post by: Marx3 on January 25, 2016, 07:49:00 AM

Seriously? :-)
17087175 it says, clearly.
I enhanced the photo a bit.
(http://i1108.photobucket.com/albums/h408/151182/Mobile%20Uploads/F9C34D4A-E0DF-44DE-8830-92591721FCE6_zpsvsrfrmw2.jpg) (http://s1108.photobucket.com/user/151182/media/Mobile%20Uploads/F9C34D4A-E0DF-44DE-8830-92591721FCE6_zpsvsrfrmw2.jpg.html)

Title: Re: What is the point of this?
Post by: Marx3 on January 25, 2016, 10:04:00 AM

It looks to be a regular rear pull-off, single mab unit with ~.078 mabs and 72 jets with pretty thick rods.

I see another guy has a thread right now, about the same carb number.

Title: Re: What is the point of this?
Post by: Cliff Ruggles on January 28, 2016, 02:36:13 AM

It's not in line with the idle system fuel supply passage, so not sure what it's function would be? 

If the passage leads to a vacuum supply it would be very weak if it would show any vacuum at all, being that high above the throttle plates.....Cliff

Title: Re: What is the point of this?
Post by: Marx3 on January 28, 2016, 06:01:08 AM

It looks like it goes to the vacum port on passenger side corner, of the front of the baseplate. I guess this is usually where the EGR get its vacum from.
The position in the barrel looks a lot like that on a Holley with vacum actuated secondaries. That's why I am thinking it is Venturi vacum source. For something, I can't figure out what.

Title: Re: What is the point of this?
Post by: jamesF on January 28, 2016, 03:14:47 PM

Quote from: Marx3 on January 25, 2016, 03:39:55 AM

I noticed this little fella, sticking out into the barrel on a 18087175, I am about to re-calibrate for a stock 403.
Is this some sort of Venturi vacuum source for the EGR?

That 18087175... is what threw Cliff off.  :)

Title: Re: What is the point of this?
Post by: Marx3 on January 29, 2016, 12:57:59 AM

Oops. Go figure :-)
170!