Several years ago I got tired of messing with aluminum tape on my oil cooler as the seasons changed and came up with a much better, easier way to do it-see the sketch below. I don't even need to remove the lower cowl; I can slip my hand in thru the lower air inlet and add or remove blocking strips as needed. I made 4 of the 1" aluminum blocking strips (the most I ever need here in Portland area is two of them); I even made a couple of 1/2" strips to fine tune it if needed. The side gripping channels are pinched down just tight enough to hold the strips in place but allow easy installation/removal. I just slip them in from the top of the channels and push the to the bottom, as many as required-takes less than 5 minutes. All material is thin approximately 0.012" aluminum.
This system has been working great for several years, but still requires adjustment as the seasons change. I am seriously thing about the ultimate solution-adjustable louvers controlled from the cockpit.
Cooler Strips.jpg