OK, guys ............. we have a person that's fairly new to Model A specifics and he's asking for a specific answer. While there was a "close" answer suggesting how long Ford used green engine paint, the right answer is:
The only AUTHENTIC paint for a Model A engine is FORD ENGINE GREEN. While some folks may choose to paint their engine another color, all Model A cars & trucks came from the factory painted FORD ENGINE GREEN. Most all Model A parts vendors have this paint available in either spray can or brush on formula.