Admiral Beez
Major
I think you're right, they're not exhaust ports. Here is the Caproni's Fiat A.74 engine and there is an exhaust manifold just like any other radial.Yes, I meant the Caproni F.5 images you showed. I suspected they'd be some kind of exhaust stubs, but if one looks at the second picture from slightly the rear of the plane, it seems there's no hole for the exhaust pipe, those blisters seem to smoothly merge into the cowling at the rear?
I now think the bumps around the engine cowl are to make space for the tappets at the top of the push rods. Perhaps these are access panels for easy adjustment? Here are the same bumps on the Macchi C.200.
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