Oh yeah, another thing; when I spray paint engine parts, I use a Map Pro torch. The torch is intended to heat things up "so I'm not really sure if this applies to this thread," But... Most of you may be scratching your head right now. Painting and a torch???
Yeah, seriously try it. I heat the part up, and when you spray it the paint will pretty much instantly cure. And, it will be safe to touch in a few minutes. Plus it prevents runs, and seems to make the paint much more durable versus air dried. I found that this really only works with Dupli-Color paints though.