Allen wrench for spark plug tool
 

I want to get an Allen wrench for the spark plug tool that came with my '73. (See attached pic). My wrench doesn't appear to be terribly worn, but a 10mm hex is a sloppy fit. I tried an 11mm but it won't go in. Was this wrench a proprietary size?

http://forums.pelicanparts.com/uploa...1462795087.jpg

I can not imagine PAG would change from your year to mine but my allen key ( aka angular screw driver ) is 10MM, confirmed with my caliper.

Use some tape to fill in the gap?

I've noticed that many modern tools are not built to the exacting standard we would expect. Try a few different brands of allen. I recommend going on amazon and buying a Stahlwille, Hazet or Gedore allen wrench and using that as the basis for your search.

im also confident its 10mm, and i use either an allen key or a 3/8 ratchet allen key bit. I love the porsche spark plug tool nice it came free =)

You're sure the receiving hole in the spark plug tool is a hex shape? Reason I say that is because some of the original tool roll spark plug sockets that i've seen have a 12 point triple square