Cliff's Quadrajet Parts and Rebuild Kits

Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: Schurkey on January 04, 2012, 10:43:18 AM

Title: Secondary "jets" + other stuff.
Post by: Schurkey on January 04, 2012, 10:43:18 AM

Carb # 17056262  '76 Pontiac 455  This carb may not be a virgin, the covers over the idle screws were missing.

1.  Read in The Good Book that "all" secondary "jets" are .136 diameter.  On this carb, I can drop a .140 drill bit into each hole and there's maybe a thousandth or two of clearance--but I don't have a .142 drill bit to verify.

The secondary metering rods (bigass L-E-A-N "DB" units) have some corrosion/pitting at the large diameter; I think that's where they "park" in the jet when the air valve is closed.

I'm wondering if the secondary jets are supposed to be that large, or if the jets have been "pounded out" or eroded to a larger size.  Will photograph, host and post later today.

2.  Primary metering rods are "45L"  What does the L signify?

3.  The choke pulloff takes 15 seconds to release.  Holds vacuum, seems to work OK, but the release time could be measured by a glacier stick.  I don't see how it's going to allow the secondaries to open in any reasonable fashion.  Defective?  Were ANY OEM pulloffs that slow to release?  I know about drilling an orifice larger, but I can't find the orifice.  Again, photos coming.

Title: Re: Secondary "jets" + other stuff.
Post by: Schurkey on January 04, 2012, 10:37:37 PM

Secondary rod corrosion ring:
(http://hbassociates.us/Quadrajet_Secondary_Rod_01.jpg)

Secondary jets (don't look worn to me):
(http://hbassociates.us/Quadrajet_secondary_jets_01.jpg)

Is the orifice under the round cap/plug?  I cannot see it inside the vacuum tube.  If it's under the cap, I'm guessing there's no way to seal the pulloff after removing the cap and drilling the orifice.
(http://hbassociates.us/Quadrajet_Pulloff_01.jpg)

Title: Re: Secondary "jets" + other stuff.
Post by: Cliff Ruggles on January 06, 2012, 04:12:15 AM

The steel disks don't wear out that I've seen.  They do get damaged on occassion and rolled over or dog-eared.

The primary pull-off should release quickly.  They get gunked up/corroded over the years, I've seen slow ones.  We have quick release straight inlet front pull-offs for that carburetor number, and anything else you would need for it.

I would replace the primary jets and metering rods, the jets get "egged out" and the rods wear some, from sliding around together for many years......Cliff