Originally the head was threaded but the top bolts are very rust prone and sometimes people will drill them out and use a bolt and nut to clamp them together. The actual manifold bolt holes are not threaded.
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company.