Idle Jets

R

Robert Legner

Member
I have a 1950 Ford with an standard 8BA, 239CID, with a 2 barrel Holley 94. When I set the idle I use a vacuum gauge. When setting the idle jets I open them until the vacuum reaches the highest point and the engine seems to run okay. Then when I drive the car and it is at the operating temperature when I come to a stop the car wants to stall. An older guy told me "the wanting to stall" when warm means it is looking for more fuel. So I open the idle jets to the point that it wants to sound like it is starting to labor and the engine does not want to stall, it runs fine. Then I measure the point where the engine runs best with the vacuum gauge and I find where the engine wants to labor the vacuum begins to fall. In other words at idle it runs best with a rich idle. Does this mean there is a problem with the idle system, or is it working correctly?
 
It sounds like you are adjusting the idle jets correctly. Have you tried adjusting the idle screw on the linkage?

Ken
 
start with the jets one turn out, on a warm engine run them out till the motor rpm's begin to drop from being too rich (flooding out) run in 1/2 turn and usually that is the best setting for most flatheads--which like to be a little on the rich side
 
To get the best setting, you have to alternatively adjust the idle screws in the base and the idle speed adjustment screw oj the throttle linkage on the side of the carburetor. Generally, you will get the mixture close, and the speed will not be just right; adjust the idle speed screw until you get the mixture right (highest vacuum). You will probably have to go through the process 2 or 3 times.
 
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