Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

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bigvette1:
Really directed at Cliff.  You modified a Q-Jet that I have origionally coming  from a 1977 Chevy.  This is used on a 73 vette, 454, cam is a Crane 272 with 219/219 @.050 and .505 lift running 3;55 gears. 

You drilled out the idle air bleed tubes to compensate for fuel drip problem, along with other mods of jets, rods, and float inlet.  The tubes eneded up really drilled out to a large size.  Maybe your records will show this.  Anyway, I want to replace these tubes with a correct size as I later found a vacuum air leak at the hose connection  by the trans modulator which changed all characteristics of the engine vacuum. 

will you please tell me what size I can order from you to replace the drilled out ones or a common size that should be compatible. If further mods are needed I can work on that later, just get the carb working properly for now.  Thanks

Jim Parks
jamesparks17@yahoo.com
847-312-7530

Cliff Ruggles:
Jim, there are no "idle airbleed tubes".  The carburetor does use idle tubes, which control the amount of of fuel available to the idle system.  There are idle bypass air holes in the baseplate, which help lower the throttle angle to keep the main system off line at idle speed (nozzle drip)......Cliff

bigvette1:
Ok thanks.  I think I was referring to the brass holes in the primary that appeared to be drilled out.  anyway here are the specs on this carb.

Carb #:  17059507
Float:  set to 1/4"
Seat:  Windowed type with hole of .125

Primary:  Jets 75, rods 44 measuring .0625/.044/.025 on the 3 steps

Secondary:  Hanger "L", rods BG

What I called the air tubes or the air bleeds in the primary are at 3/64's or .046
If this is still confusing Cliff, give me an email address and I will send off some pics of that area that I am referring to.

I guess my question is does this setup seem correct for the car (73 vette 3400lbs) and engine (454 with cam specs listed)  parameters that I gave in the initial post?  Thanks again. Jim

Cliff Ruggles:
cliffshp@embarqmail.com

bigvette1:
Cliff, at this point I have the Q-Jet on the engine and running.  It has been on the shelf since summer so it needs some run time.  However, with the idle screws out 5 1/2 turns vacuum is at 17-18" and fairly stable.  Some hunting but nothing different than other carbs I have to play with.  The problem you worked on this carb a 2nd time was nozzle drip even when idled down to an acceptable level.

 Well... I see no nozzle drip at this time so the drilling on the air bleeds (believe that was what it was) seems to have corrected this issue.  The only problem I have to work on is there seems to be a "hitch" or almost like a notch in the throttle movement.  Can't tell yet if it is the acc. pump or throttle mechanism binding somewhere.  Overall all if we did not have a ton of snow in Chicago I would take the vette out and see how the carb runs under load.  At idle it is very positive.  I will still send off some pics of the area that I am referring to.  Thanks.

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