HOW TO PAINT POLISHED ALUMINUM ENGINE COMPONENTS?

Well, here is my $0.02. I am not a professional painter, but I have been painting for 45 years. First, you must understand that aluminum is a metal, so it can be painted. And like all metals, certain rules will apply. You will need some primer on the part. It will need to be a DTM (direct to metal) primer. But before spraying primer, the metal must be prepped. Polished aluminum is smooth. You need to scuff the metal with some sandpaper for mechanical adhesion of the primer. 320 grit will do. Then sand the primer and apply paint.