Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 exptools 1/6/84; site ihuxk.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!ihnp4!ihuxk!rs55611 From: rs55611@ihuxk.UUCP (Robert E. Schleicher) Newsgroups: net.auto Subject: Re: Camless valve operation Message-ID: <858@ihuxk.UUCP> Date: Fri, 18-Jan-85 14:13:32 EST Article-I.D.: ihuxk.858 Posted: Fri Jan 18 14:13:32 1985 Date-Received: Sat, 19-Jan-85 01:30:34 EST References: <6848@watdaisy.UUCP> <1737@zehntel.UUCP> <6852@watdaisy.UUCP> Distribution: net Organization: AT&T Bell Labs, Naperville, IL Lines: 17 For people who've been wondering what the term "desmodromic" (sp?) means, it's a term that's been used in Road and Track articles (in particular, one describing the engine used in 1930's Mercedes-Benz Grand Prix cars) in which there are no valve springs to return the valves to a closed position. Instead, some form of positive return action is used. In one variant, a separate cam lobe is used to close the valve. This implies two cam lobes per valve, perhaps on separate shafts. In another theoretically possible variant, the cam lobe has a slot in it through which the end of the valve stem "travels" as the cam shaft rotates. Thus, the valve is both "pushed" and "pulled" by the cam lobe, rather than being pushed by the cam lobe and pushed back by a spring. In theory, desmodromic valve operation should allow higher RPM operation without valve float, although there is a complexity penalty. Bob Schleicher ihuxk!rs55611