How to knife edge your throttle body butterfly valve.

[douglas vincent]

Technically you are putting a chisel edge on it, since a knife edge is grinding both sides. You ONLY WANT TO GRIND THE BACK SIDES!!!!!!

If you have nothing better to do......

Two screws hold the valve in place. Remove screws and pull plate out. If it doesnt move, its just sticky. The valve will pull out TOWARDS the intake manifold.

You want to knife edge ONLY the side which is not closing off the air flow in the throttle body. While the valve is still in the throttle body, put an X on the valve sides where the valve is closing off the air flow so you don't fuck up and grind the wrong side. Don't ask me why I know this.....

Next you need a grinder, preferable slow speed, and a bucket of water next to the grinder. This valve gets HOT!

Turn grinder on. With your thumbs and forefingers, grasp Valve so the screw holes are parrallel to the grinder wheel. The X, or sealing side of the valve is UP!. Lay the valve on the top of the grinder wheel and slowly turn the valve from left to right at an even pace for 2-3 left right cuts. Now look at it (if hot, dip).

At this stage you will see a correlation on how much you are cutting the back side and at what angle, and how close you are getting to the pivot points on the side of the valve. I ground down to the edge of the pivot point band that you will see when you remove the valve.

Keep grinding away until you are about 1/32" or so EVENLY away from the sealing point edge. At this stage, depending upon the angle you have been cutting, you may or may not need to back cut the edge you have been cutting. i.e. the angle you just ground may be not much of a chisel edge. If its too steep. you really didnt accomplish much. So grind away at the back until it looks good and angled. This means that you should have about 3/16" of the valve ground away at an angle.

Obviously there is only one edge that faces the incoming air flow and that is the most important. But the trailing edge of the valve might as well be ground down as well, just like the ass end of a car is tapered to help with air flow.

Thats basically it. I guarantee this not one whit. But I did it and now you can too!

If I get a digital camera again I will post some pictures......

Good luck!

[206er]

I used a file on the butterfly and a dremel with a carbide on the throttle body.
Im not convinced that there are a whole lot of gains from this mod but then again I did mine when it was out while I was swapping short blocks.

[douglas vincent]

Yeah, I have 3-4 throttle bodies laying around, so I just yanked one out and did it while I had the opportunity. Doesnt hurt, I hope.