Posted by Art H on May 15, 2002 at 23:06:57:
In Reply to: Bore Size and piston valve stroke posted by Dave on May 15, 2002 at 17:24:28:
If you take out a piston and look at the "ports" you will find the two where the air goes in with a small space between them. Now imagine bringing those holes closer together, until the space between them is as small as possible. In that limiting case the piston stroke must be equal to the diameter or "bore" of the valve tubing. In that sense a larger bore requires a longer stroke. BUT in practice the ports are not usually put that close together because it would require more compromising inside the piston and because it would increase the tendancy to leak. That's why King valves have rather long stroke in spite of their small bore. The Conn "short-action" valves discussed below were a clever solution to the problem.