Actually a 6 pointed allen wrench will work. They make a cylinder base
wrench that has a 6 point hex on the end for these internal wrenching nuts.
Try your local EAA chapter tool library or an older A&P as they were very
popular in the 50s.

--
Cy Galley, TC - Chair, Emergency Aircraft Repair, Oshkosh
Editor, EAA Safety Programs
or

Always looking for articles for the Experimenter

"DAVE" wrote in message
...
Hi, I'm looking for the 12 point serrated drivers used on the cylinder
nuts
of an 0-320A Narrow Deck. I checked out the Autmotive Parts shops in my
local town but they only had them available in metric sizes, not the 1/2 "
and 3/8 " (I Think) needed. I have a set of Lycoming cylinder wrenches
for
convensional nuts, as used on my 0-290d, and wanted to adapt them. Any
Ideas out there?? Dave.