Painting questions, what nap roller to use? Options

[swood]

Just Kidding.

I'm cleaning out the engine bay, pretty much sanding down all the glue, removing all the dirt and wire brushing out the rust (just surface, no deep rust). The side and rear panels don't need much in the way of repair, so, can I just lightly sand them and tack cloth it to prepare it to recieve paint? I have a self etching primer for the firewall that's going on nice and smooth.

My color is Palma Green Metallic. I'm not sure if metallics are meant to be color sanded much, if at all. I guess that question is more for the exterior, the bay I'm using a single stage paint, so as long as it doesnt run I probably won't worry about the sanding.

[Slowpoke]

I hesitate to answer this. As soon as I say don't do something, someone will say I do it all the time and it works great.
I would think most painters would not recommend to top coat over an old top coat without some type of primer or jam-sol or something to open up the old paint. On an engine compartment it is important to get it as clean as possible with a strong cleanser. Then blast or brush to bare metal where there is rust. Acid etch prime where you have bare metal (it does no good over any type of coating already there). Wet sand all the old paint acid etch primer and urethane prime the entire area. Wet sand again, let it dry a day and top coat. Some people skip steps and it works great. Other people skip the same steps and it falls off in two years. YMMV
Painting is getting really expensive. It cost me also $1500 in materials for an average condition car to follow all the steps the paint people recommend. 10 years ago it was alot cheaper. But, when you have a paint problem now the paint company sends out a guy with a microscope to examine the paint and what you did or didn't do. Just not worth skipping steps, I don't think. Good luck (IMG:style_emoticons/default/smile.gif)