Ford NAA idles too fast how to adjust

[soaked]

It is possible to put the new throttle shaft in, without clocking it properly. Gives idle butterfly position "down in back" when it should be the same as at the movies,
"down in front."

The two carbs on the left are 8n tsx 241B clones.
Your idle set screw should be behind the stop peg, like the new carb on the right, and be adjusted from the rear. (not from in front of the carb)

When the throttle shaft is wrong, the link arm from the gov has to push over the top, instead of down underneath.

 

[Garryowen]

Here's what I have found so far. I used the old throttle plate. It had nick on it's edge. It was installed with the number up and the proper direction. I can't believe that a small nick can cause this problem.

 

[used red MN]

She said to leave a small fingernail gap at to top

The fingernail gap is likely to be how to set the idle stop screw after installation. The throttle plate is to be installed centered to be able to close the air to the engine as well as it possibly can. My method to center it properly is install the throttle plate on the shaft with the screws snugged down so the plate is just loose enough to still move a bit. With the stop screw back way off twist the throttle lever on the shaft to close the plate in the carb throat. Applying a bit of pressure to keep the plate closed lightly tap the plate with the tip of your screwdriver this will center the plate. Continuing to hold it shut tighten the screws. I doubt the notch in your old plate was the problem, it was just not centered properly.

 

[showcrop]

Check for a loose throttle plate shaft. It could be sucking air there. Then check for leaking intake manifold gasket by spraying WD-40 at it to see if it speeds up.

 

[soaked]

When you lowered rpm from 1100, unscrewing the idle speed screw let the end of the screw move closer to the stop peg, closing the throttle. As the screw has been unscrewed further, is the threaded end actually touching the stop post, or is linkage preventing closing?
This is a tsx241B from 8n. Its not that precise taking measurements from under the screw, but gives an idea.
Its about half throttle with a 1/16" opening, and a 400 -500 rpm idle.

Will rpm lower if push with a finger, or if unhook the link rod and work the carb by hand?

Some on the 9n, 2n & 8n board have had new throttle shafts where the ball that connects to the link rod was too big, and caused binding.