Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
Rebuilt qjet won't idle lower than 700 in gear
Kyle:
Hi everyone, I bought a rebuilt carb from another Firebird owner who had not yet installed it. It is not one of Cliff's. The carb is a 68 service replacement Pontiac.
I pulled the original 2 barrel manifold and carb from my 350 and put a 68 stock 4 barrel manifold and this carb on. Did not change any timing settings. It was running perfectly before the swap. The engine is a low mile rebuild, 30 over, a xe256 cam, running 9.2 compression.
Idle adjustment screw backs right out still wont get it lower than 700 in gear. 1000 in neutral. 15 in vac at best. Choke is not connected, but assembly is there. All vac orifices plugged.
Also runs hotter than before.
People behind me smell gas.
Any ideas?
Thanks!
Kyle:
Oh yeah, I can stall it with my hand over the choke horn.
omaha:
sort of sounds like the ported source is not being used for the vac advance. check timing at idle, it should not "move around" and you will not get a steady idle if it is moving around. Mke sure you are using the ported source for the distributer and check the timing at idle. Did you set your mixture screws with a vacuum gauge? (this is another good source of information to tell where your adjustment is at). Start with the basics. Just because it ran fine with the 2 bbl does not mean that the 4 bbl will be automatically set right for the engine. good luck!
Kyle:
--- Quote from: omaha on June 19, 2014, 04:55:02 PM ---sort of sounds like the ported source is not being used for the vac advance. check timing at idle, it should not "move around" and you will not get a steady idle if it is moving around. Mke sure you are using the ported source for the distributer and check the timing at idle. Did you set your mixture screws with a vacuum gauge? (this is another good source of information to tell where your adjustment is at). Start with the basics. Just because it ran fine with the 2 bbl does not mean that the 4 bbl will be automatically set right for the engine. good luck!
--- End quote ---
The vac advance is connected to a T in line with the power brake line that is connected to the rear baseplate of the carb. The idle is steady, I just can't get it to go lower than 700 in gear or 1000 in neutral. The screws were set with a vac gauge, 15 in is the best I get.
Thanks!
Kyle:
Any ideas? Please? :)
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