I am planning to paint the underside of my hood this weekend. Do I need to use primer first? or just sand smooth, clean, tape, spray final color. I was going to use spray can high temp black.

Personally, I don't use primers in areas like that.

To do any painting properly you should always use a primer (unless you are painting over a freshly painted area).

Primer is designed to stick to the surface and stick to paint.

But it really depends on what your intent is. Are you just trying to make it presentable or are you trying to make it look custom show quality.

When I painted the back of my hood I just used a good spray paint. I was just trying to get a color coat on it to make it look better than raw fiberglass.

And when I was working along the frame (had the engine and tranny out, etc) I sprayed Rustoleum on the frame. There was no rust (well, not worth mentioning anyway), but I just wanted to put a protective covering on the metal.

In places where I wanted a better quality paint finish, I prepared the surface better and used primers and sealers and top quality paint.

Thanks for the feedback guys. I got rained out this weekend, rain both days. I'll try another weekend.