Here's a particularly unusual part:
Any guesses what that's for?
Yeah, probably not. I won't keep you in suspense.
I had two reasons to turn a perfectly nice acetal cylinder into this odd shaped part. The main reason was I wanted to get rid of the thermostatic idle valve entirely. I've been running with it disconnected and I'm convinced it's screwing with my idle. So as you can see I milled that whole part off and this adapter fits in its place. The reason I didn't just block the thermostatic valve is for packaging. The front facing idle air intake was causing my intake elbow to be further forward than it needs to be otherwise, which in turn was complicating the radiator plumbing. This adapter relocates the idle air inlet to the bottom left of the throttle body.
I'm not sure acetal was the right material to use for this, but it is a heck of a lot easier to machine than aluminum and I didn't have any ABS on hand. The problem with acetal (delrin) is you can't glue it. I'm not sure how the silicone RTV I used to seal it to the idle valve will hold up.
This is the other side of the idle valve:
The red circle is the outlet of the PWM idle valve. The blue area is where the thermostatic valve exhausted. Funny that the thermostatic valve area is so much larger. I expect I'll have to crank in more idle air screw to work without it.
This is the only "before" picture I have. Anyone have a shot of the unmolested idle valve for comparison?