Chevy Orange Engine Paint Question????

[dandansuperman]

I am painting my engine with Plastikote Chevy Orange engine enamel. I have spent hours sanding and cleaning the engine so I am ready to paint. I started putting on the first couple of coats and it seems really thin. The paint shop owner told me not to prime the engine because the paint will hold up better without it. I figured I would let it dry for a few days and then apply some more coats. Everyone I have talked to said orange paint is just really transparent. Should I go and buy primer to put on first, or should I let it dry and put some more coats of the enamel on? Please give me some advice.