Cliff's Quadrajet Parts and Rebuild Kits

Quadrajet Problem Solving => Dialing in your rebuilt Quadrajet carburetor => Topic started by: Frank400 on August 15, 2015, 06:31:35 PM

Title: secondary air bleed
Post by: Frank400 on August 15, 2015, 06:31:35 PM

Not sure is this is how we should call this, but here's my question anyway.  That long thin tube that is attached in the air horn and goes down into the secondary well, called "secondary tube restriction" by Cliff in his book, is .026" from the factory.  Carb is a 17057202, large .120 main air bleed Chevy unit.  Would enlarging it to .036 lean the secondaries ?  I'm asking because recipes one two and three all call for a .036 size. 

    I know about the other variables on the secondary side, just wondering if it really acts as an air bleed as we know them, enlarging leans out, getting them smaller richens.

   

Title: Re: secondary air bleed
Post by: novadude on August 20, 2015, 07:02:23 AM

Good question, as I was also wondering how much impact this has on secondary a/f curve.  My guess is that larger is richer when the secondary throttle first opens and leaner on the top end.  I've never really experimented with different sizes though.

Title: Re: secondary air bleed
Post by: 429bbf on November 08, 2015, 05:07:06 PM

my understanding is its all fuel until the fuel is pulled from the big tubes.so making them a little larger would richen the secondaries instantly until the wells are pulled dry. i would like the  the boss can chime in and correct me if I'm wrong because thats my understanding.fwiw

Title: Re: secondary air bleed
Post by: Cliff Ruggles on November 10, 2015, 04:07:01 AM

The long tubes extending into the main fuel wells are for emulsion, so basically an "air-bleed" for secondary fuel to the nozzles.  They do have an impact on the fuel curve with any metering rod used, so keep that in mind when opening them up.  The "recipes" we provided in the book are dyno and drag strip tested, but still should be used as "basic" guidelines for tuning.......Cliff

Title: Re: secondary air bleed
Post by: 429bbf on November 21, 2015, 08:04:29 PM

thanks cliff. i read the post wrong i thought they were talking about the acc. well tube my mistake.fwiw

Title: Re: secondary air bleed
Post by: Landshark on December 03, 2015, 03:20:08 PM

Not to hijack this thread, but how are those tubes removed. I got and old Q-jet from a friend, and when i disassembled it the P.O. had cut the tubes of by about 1/2". Some heat and gentle persuasion?  ;)

Title: Re: secondary air bleed
Post by: Cliff Ruggles on December 04, 2015, 03:12:06 AM

In most cases they come out pretty easy.  We gently pry them out with a small pair of wire cutters, they aren't fussy.....Cliff