Throttle valve R&R, 1.7 liter et al Options

[r3dplanet]

So I decided to pull the throttle body (valve) from my car in order to rebuild it. The throttle valve had a tendency to leak and stick. It was also moderately dirty. At the time I was on a personal mission to pull and restore every major component of the D-Jet system. Since then, I've performed similar operations on the MPS, AAR, etc. Perhaps I'll document those operations in a similar way.

My car is a 1971, but the engine is a 1973. I know that other engines use a top-mounted throttle valve, but it's actually quite similar to the side-mounted units like mine.

I realize that this isn't superorbital propulsion engineering, but it might be helpful to somebody.

Here's the original setup. You can clearly see the part number 022 133 067 under the muck, along with various scratches and nasties.







In this photo you can see that there's quite a gap around the brass air valve and inner diameter of the main bore. It seals if the valve is fully closed, but even the smallest relief of the lever allows air to pass.

[r3dplanet]

Now pull the shaft.







You can see in the next couple of photos that the shaft housing likes to attract dirt because of the strong vacuum. The aluminum wears away over time, the gap around the shaft enlarges, and more dirt can get sucked in which abrades the housing further and faster. This right here is the Achilles' heel of our throttle valve. There are no bearings or bushings to protect the aluminum.





The fix for this? Bronze bushings. Neither I nor my machinist was able to find metric bushings that would work exactly right, so I ended up cheating and using US non-Standard ones instead. We used Oilite AA-306-11B bearings. They have 5/6" inner diameter and 3/8" outer diameter. The other reason we used non-Metric sizing was because we'll have to use a reamer, and a 5/16" reamer was much easier to find. I'm almost ashamed to admit this. I've gone to great lengths not to use US non-Standard anywhere on the car. But believe me when I say that this works perfectly.