Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
nozzle drip again
bsblguy:
It is on ported vacuum. Timing set to 12, stays there with line connected or not and advances with slight movement of throttle.
Shark Racer:
Are you setting your idle mixture and idle speed in drive or in neutral?
bsblguy:
A little update. Changed the idle down channel to .055 (have an old carb laying around) and upper air bleeds to .048 and it is much better. Still get a slight nozzle drip but not constant, just a very small amount at times. idles at about 930, 650 in drive drops to about 560-570 when ac on. I've set mixture screws in park and in drive, didn't seem to matter. Idles rougher than I think it should. I compare it to my 455 TA 4 speed idle set at 800 and can put in gear let clutch out some with brake on so idle speed drops to 650 and it is smooth and that engine has more power than this one. Also compare it to my brothers firebird 400 and it is smooth in drive with ac on, ac barely drops rpm. I did let a little air in from a vacuum line and rpm did go up a little. do I need to increase upper air bleed some? It performs great, just this idle problem.
omaha:
I would not mess with the airbleeds but would increase the bypass air slightly and maybe open up the idle needle ports a little (although I do not know what they are at now, maybe they are ok. Do you have full adjustability with the needles? If so leave them alone.) Still think that the thing could use just a tiny bit more initial timing, maybe just shy of 15 btdc. The cam must be bigger than you think is what I am thinking. Argh, jus tear the motor apart and take a gander at the cam. (jus kiddin) although you could measure the lift at the valve with the valve cover off?? Hope you are using a vacuum gauge to set the idle, that is the best way to do it.
Cliff Ruggles:
Checck the timing when the trans is placed in gear, to make sure it is rock solid, and not retarding a few degrees. This would cause a greater drop in rpms when a load is placed on the engine....Cliff
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