On Tue, 29 Apr 2008 10:21:39 -0500, Roger Shoaf
wrote:

Tapping cast iron is not too difficult, especially if you are using sharp
tools. One thing you might want to consider is to do it on the vehicle,
cold with the engine off. You can rig compressed air to flow in to the
tail
pipe and that way the air pressure will blow the swarf out.

You can loosen something along the way to allow a little pressure to
escape.
I think about 10 to 15 PSI should do the trick without blowing anything.



I see what you mean. I found some cast iron elbows and drilled by
hand. It drilled quite easily. Of course I didn't make a straight hole.

--
Wayne D.