Hot Rods head nut covers what's the trick?

So I decided to spruce up Dad's '41 flathead and ordered those chrome head nut covers from speedway. is there a trick to pressing them on? I can tap some on but others there's no room for a hammer and a block of wood. Am I missing something here?

 

Your missing the nut cover.

 

Guy over on the fordbarn had the same luck with the speedway covers, ordered new ones from offy and they slip right on