First off... Thank you Dan for making me think!!
So, today the sun is shining, temperature 48F, light breeze in Tacoma, Wa.
That means today the TB came off the engine and we took pictures.
What I found was an education for myself, which I will share.
The detent position of the throttle plate, when the engine is off, is not the closed position. Because the TB is computer controlled, the detent position is actually at 31 degree, which allows them to move the plate in either direction and not hit an end stop.
The full closed position shows about .500 inches of metal below the throttle plate, the idle position 17-19 degree's is in that lighter colored area closer to the closed position. Then there is the darker band which is where the groove is going to go.
You'll also notice the contouring of the venturi, my recollection on the dimensions were obviously off (pictures never forget) so there is plenty of meat to put the groove with the large bit, there may be a couple of spots that it may come through... they will be filled in before any cutting occurs
Now the pic's
Off/detent position
Closed position
Idle position 17-19 degrees
Intake manifold
and that is my 2007 Chevrolet Avalanche 5.3L Vortec TB, and now I am also more educated than before
Karl Fortner
Tacoma, Wa.
Gadgetman Tacoma