I picked up an extra TB, and I was looking at it, and noticed that there were quite a few sharp edges in it.
Basically, GM had it cast, and then machined from the rear, but they never cleaned up the sharp edges. In addition to that, that little step at the base of the MAF sensor is cut off square at the back from the machining, so it is partly blocking the top of the butterfly.
Anyhow, I went at it with the Dremel, I didn't make the opening around the butterfly any larger, but just cut and rounded all the sharp edges.
I also cut and rounded the edges at the opening of the throttlebody, and I cut down the step that sits behind the MAF screen. I figured that the step was the reason for the rough idle with the screen out.
So, I installed the thing (had some difficulty, the f***ing gasket leaked the first time, and water was blowing into the intake, causing number 1 cylinder to misfire).
It works much better now :D
Basically, GM had it cast, and then machined from the rear, but they never cleaned up the sharp edges. In addition to that, that little step at the base of the MAF sensor is cut off square at the back from the machining, so it is partly blocking the top of the butterfly.
Anyhow, I went at it with the Dremel, I didn't make the opening around the butterfly any larger, but just cut and rounded all the sharp edges.
I also cut and rounded the edges at the opening of the throttlebody, and I cut down the step that sits behind the MAF screen. I figured that the step was the reason for the rough idle with the screen out.
So, I installed the thing (had some difficulty, the f***ing gasket leaked the first time, and water was blowing into the intake, causing number 1 cylinder to misfire).
It works much better now :D
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