Idle screws not affecting the idle.
#1
Idle screws not affecting the idle.
My idle screws are close to the point of coming out, and the car still idles, starts and runs great. Am I overlooking something, or is it time for yet another carb rebuild?
'72 350 4bbl, '71 Q-jet on it, new gaskets.
'72 350 4bbl, '71 Q-jet on it, new gaskets.
#2
Are you sure you are turning the idle screw & not the mixture screws? The idle screw is in front of the linkage and is mechanical in nature. You turn the screw the idle changes.
http://www.hotrodders.com/forum/quad...ion-63050.html
The mixture screws are at the bottom of the carb to the left & right of the fuel inlet.
http://www.hotrodders.com/forum/quad...ion-63050.html
The mixture screws are at the bottom of the carb to the left & right of the fuel inlet.
#3
Turning out the idle mixture screws in on the front of the carb richens the mixture. These are used for lean/richening the idle circuit and should not be used for idle speed which is controlled by the screw near the linkage connection at the carb. Why are the screws out so far?? Usually they should be turned out about 3-4 turns.
#4
Hey, if it runs well....
I just ran through several carbs last weekend, and one main body didn't idle well, while another one did. Same modifications and internals to both. Strange, but we're talking 40+ year old cores here.
That could also mean there's a minor air leak somewhere, so the idle screws have to be really rich to compensate.
I just ran through several carbs last weekend, and one main body didn't idle well, while another one did. Same modifications and internals to both. Strange, but we're talking 40+ year old cores here.
That could also mean there's a minor air leak somewhere, so the idle screws have to be really rich to compensate.
#5
Turning out the idle mixture screws in on the front of the carb richens the mixture. These are used for lean/richening the idle circuit and should not be used for idle speed which is controlled by the screw near the linkage connection at the carb. Why are the screws out so far?? Usually they should be turned out about 3-4 turns.
The idle being affected was something I read, about adjusting the screw until the idle gets rough, then turn it a turn back.
#8
The idle mixture screws restrict the flow of fuel through the idle ports as they are tightened.
There are other carburetors, including a number of European ones, that have idle air screws, which restrict the entry of air as they are tightened - I suspect that that is the reason for the confusion.
- Eric
There are other carburetors, including a number of European ones, that have idle air screws, which restrict the entry of air as they are tightened - I suspect that that is the reason for the confusion.
- Eric
#10
I think the Holley 5200 used on the Ford 2.3 is like that, or at least that is how it acts! I have never got a real confirmation on it yet...
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July 6th, 2012 06:45 AM