Throttle Body Boring

[flyer1]

I chucked my stock tb in my lathe and bored it out to 62mm. I then made a blade out of a piece of alum I had laying around. Question, does anyone know how much daylight you should see around the edges when looking into the light? I am not sure if it should be closed tight or is some clearance ok. I know you can adjust the opening with the screw but I am not sure about how tight of a fit it is to be.

[Muad'Dib]

I'm not sure on how to measure by light, but i have heard of another way to do it.

Take a strip of paper and put it on one side of where the valve closes and close the valve. Now try to pull the paper out. If the paper rips, or is tight to come out then the valve closes too much. Once you can pull the piece of paper out smoothly, then its adjusted correctly.

You definitely don't want it tight... you will ruin the TB by cutting a ridge inside with the valve slamming shut.

[flyer1]

I guess I did not ask my question correctly. I can adjust the stop screw so that the valve won`t touch but my question is how perfectly round does it have to be considering it was hans finished with a file? If you take a new one (non bored) and back off on the stop screw will you see daylight?? I have a few high spots and it is extremely difficult to get it perfect and I am wondering how critical the fit has to be. Thanks for the comment

[Muad'Dib]

I guess I did not ask my question correctly. I can adjust the stop screw so that the valve won`t touch but my question is how perfectly round does it have to be considering it was hans finished with a file? If you take a new one (non bored) and back off on the stop screw will you see daylight?? I have a few high spots and it is extremely difficult to get it perfect and I am wondering how critical the fit has to be. Thanks for the comment

Your original question was nothing like what your asking now

Anyway, your going to want it pretty close... you can always get it the best you can and see if the IAC can compensate for the excess. If your idle is high then you know its not good enough.

[flyer1]

Ok good that was the answer I was looking for. When I finish my 4.9 build and try it out I will let you know how it turned out. Thanks again

[SilverXJ]

There is a method for adjusting the screw. IIRC its just to you can a bit of light past it. You won't want the blade touching the sides.