...while keeping out leaves etc., they also (in my opinion) significantly reduce the amount of "free-flow" air admitted by the vents. On the 240, this requires using the blower fan at speeds where formerly it wasn't needed. I estimate they reduce the intake area about 80%—with any potential "ram air" effect being negligible, despite IPd's claims.

So I removed them (almost as hard as installing), and did the same for my 940 vent cover. The 940 didn't "free-flow" as well as the 240 to begin with, and the cover also reduces the intake area by about 80%.

The 940 has a mesh screen that I pulled up to the vent opening and secured with some small tie-wraps. Too bad the 240 lacks that screen.

I still have the 940 cover, but don't think I saved the ones from the 240.
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.