Drilling these studs can be a real bear! You need to start with a very small
drill and work your way up. Slow speeds and high pressure. Lubrication. Once
the bit losses its edge the material work hardens making drilling even more
difficult. For the one with a stub you can try mig welding a nut to the
stud. The new found wrench surface and heat shock will often get the stud
loose enough to turn out.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Alistair Bell
Sent: Tuesday, July 03, 2012 6:07 PM
To: vanagon@GERRY.VANAGON.COM
Subject: exh stud - drilling out is tough

I'm fixing up an old spare WB I have and I successfully extracted what was
left of 6 of the 8 exh. studs/bolts. Last 2 broke off, one flush and one
with a stub. Working on the flush one, I able to drill in about 1/4" but no
more. It is as if I have hit some harder steel. I've blunted about 7 drills,
and even a brand new cobalt drill does not want to make any chips.

I'm puzzled as to why it all was going well until 1/4" in. This is with
engine on an stand, I can't imagine the dismay and annoyance if I came
across this kind of thing when trying to drill out a stud with engine
installed.

alistair