Well drat. I discovered this morning that at it's uppermost limit of travel, the lever arm on the side of the butterfly hits the cowling. I tinkered with this thing most of the day trying to figure out how to make it work.

After much head scratching, I just rigged it so that instead of 90 degrees of movement to go from full open to full closed, it has about 45 degrees of movement and travels from full open to about 45 degrees closed.

This rigging was just a simple fix for my clearance issues, but the more I think about it, the more I like the idea that if the cable jambs up or something, it isn't likely that I could find myself in a situation where I'm stuck with all the cooling air shut off to the oil cooler.

The whole idea here is to choke down the air to the oil cooler and potentially help get the oil temps up during winter operations, but I question how much you really need to choke it down. 45 degrees should head it in the right direction.

If I fly for a bit and find that I don't use this feature, I may just remove it entirely.

I don't like that the control cable for this is just held on with a brass pitch bolt. Also, the lever arm to shaft isn't splined, just held in position with a tension bolt.

Because I'm a belt and suspenders kind of guy, I put a couple of joggles in the cable and applied lock-tire to the set screw. Even if the screw comes loose the cable can't really come off. I also cross drilled the lever to the shaft with a #50 bit and ran a double wrap of safety wire through it.

I hope this feature is worth all the trouble. I've put a ton of effort into this, but at this point I've got is as bulletproof as possible.