Not sure if its "proper", but here is what I did. I too have painted engines in the past that didn't last. Make sure the engine is clean of all grease and grime, I then used a wire wheel and stripped all the old material off. I then cleaned with thinners, "blew" the engine all off with air compressor. When I was certain it was clean and dry I applied an etching primer to cover the bare metal. When it was dry I scuffed with a scotchbrite pad to ensure the base coat adhered. Then I appied 3 coats of clear. I was quite happy with the results, Mine has been run @ operating temp many times and a few short drives with no issues as of yet. I did not use a sealer it might be a good idea? Couple pics in my photo bucket of the finished product.
