Mag housing rotation

I'm mounting the oil cooler on the firewall of my RV-7 (not looking for critiques of that decision). I have what I think is good clearance to the left mag at the moment, but might have clearance issues if the mag housing needed to be rotated 10 - 15 degrees.

My question is, how much rotation am I likely to need in routine service?

You can insert the mag

at at any initial angle you wish when you insert the mag into the case (+- one tooth). Just follow the published procedure (don't have handy at the moment), and bias the mag head a little away from any potential interference. This should not present a problem with the oil cooler position unless there are obstructions in the "other direction". I would do a trial install before I mounted the oil cooler to be sure...

There are a couple angles where the impulse won't catch. They're pretty extreme angles though. Just hold the mag up in front of you with one hand in the approximate position you want to use, then turn the mag with your other hand to make sure the impulse will grab at that angle.