Airmotive FI Idle Stop Screw

[dbuds2]

Has anyone ever experienced the idle stop screw rotating to increase the minimum idle RPM during a flight? This is the screw with spring tension that sets the arm closed limit. During a landing it seemed like landing with a tail wind as I kind kept flying down the runway. When I braked and turned off, I noticed I could not get the idle lower that about 1100 rpm, usually I idle at 600 rpm.

I don't know if this is the cause or not yet. At first glance, the arm is still bottoming out on the screw .

 

[RWoodard]

I recently had a real DUH moment with my throttle cable/idle stop. Long story short is that when I reinstalled my engine and throttle cable, I incorrectly positioned the cable hold-down nuts that properly position the cable fore/aft. I started fooling with the idle stop screw thinking that it somehow rotated under the spring. Turns out nothing had changed with the idle stop screw. I had shifted the entire cable so I could no longer get full throw to get all the way to the idle set screw. An 1050rpm idle really does increase landing roll!

Just a different angle to consider…

 

[lr172]

Unlikely. That style of idle speed screw is used on about every plane flying around and was used on millions of cars back in the carb days.

Can't say that it couldn't happen, but I would be looking for a different cause. Might check to be sure the linkage to the idle shaft is fully intact. That is the square bar with the idle mixture star knob in the middle. It also has screws that clamp the fittings on to the shaft

 

[dbuds2]

thanks guys and agree, the set screw should NOT be the cause, I will be looking at the whole cable and mount system today and will post my findings.

 

[dbuds2]

I looks like the cause was my alignment shim moving and pulling the whole cable end farther away from the throttle body. When I got close, the throttle stop was about .030 away from the stop set screw. I'm going to move the alignment shims around so gravity and vibrations don't move the to change the position.

 

[lr172]

I looks like the cause was my alignment shim moving and pulling the whole cable end farther away from the throttle body. When I got close, the throttle stop was about .030 away from the stop set screw. I'm going to move the alignment shims around so gravity and vibrations don't move the to change the position. View attachment 95363

i don't think wedge shims are a good idea in that application. by their nature, they are always trying to squeeze out. if you are going to keep them, you need a way to lock them in place.

better to put the taper shim between the white bracket and the angle. the rivets or screws will lock it in.