Posted by Rick Denney on May 28, 2002 at 21:28:35:
In Reply to: Re: Re: Re: 186 BBb vs CC centering/agility posted by Klaus on May 28, 2002 at 17:56:30:
Klaus, just for your information: The word is swaging, not swedging. That's why you could not find it in the dictionary. The pronunciation would be almost the same, which is probably why it was misspelled where you saw it written.
A swage is a metal-working tool that shapes metal by means of pressure or impact.
In this case, it is a pair of pliers that wraps around the outside of the bushing, and works it to a slightly smaller size. The valve rotor is turned (very slightly) on a lathe to make the bearing surface flat and smooth again, and then lapped into the smaller bearing. It is exacting work, but I'd rather attempt that project than rebuilding pistons and casings.
Usually, though, rotary valves don't leak, because if the bearings wear to the point that the rotor surface drags on the casing appreciably, they either make intolerable racket or they don't move at all. Some knowledgeable types think noise for worn bearings is much more common than noise from work linkages. I'll defer, despite that my small sample doesn't agree.
The first place I check when I suspect a leak is the water key.
Rick "who thinks 186 CC tubas are quite different from 186 BBb tubas" Denney