---------------------------------------------------------- Engines-List Digest Archive --- Total Messages Posted Sat 01/13/07: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:38 PM - Lycoming Camshaft Question (J. Mcculley) ________________________________ Message 1 _____________________________________ Time: 03:38:24 PM PST US From: "J. Mcculley" Subject: Engines-List: Lycoming Camshaft Question In Lycoming 4 cylinder engines there are only 6 cam lobes. If I have deduced it correctly, the four exhaust valves are each driven from their individual cam lobes, but the intake valves share cam lobes as follows: Cylinders #1 & #2 share the same lobe and #3 & #4 share another lobe. This arrangement results in only 6 total cam lobes being necessary. (BTW, in the 6 cylinder models, there are 9 lobes for the same reasons) My questions are the following: 1) For those of you with considerable experience in tear-down of these engines for problem analysis or overhaul have you noted any correlation in observed cam lobe wear of the lobes that drive the intake valves versus those lobes driving exhaust valves? Since the intake lobes make twice the number of follower contacts per crankshaft revolution the rate of wear would seem to be greater, if all other variables are constant. 2) Assuming that one of the lobes driving a pair of intake valves does wear significantly, what engine operating symptoms would be a clue to this event? 3) How would this symptom differ from that of an exhaust valve lobe wearing to a similar degree? 4) Which situation, if not detected by oil analysis and cutting open oil filters, would be easiest to recognize via engine performance degradation? Jim McCulley -------------------------------------------------------------------------- ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message engines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Engines-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/engines-list Browse Digests http://www.matronics.com/digest/engines-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.