[AT] OT- Briggs and Stratton valve clearance

k7jdj at aol.com k7jdj at aol.com
Thu Jun 23 17:45:48 PDT 2016


Not a lot of traffic so I thought I would post a question about a 70's vintage  5 HP Briggs engine.  The engine is used on a plate compactor so it is subject to extreme vibration.  I made the mistake of letting someone else use it and got a report that the engine was running extremely fast and you couldn't adjust the speed.  Quick check and it was obvious the throttle plate had fallen off the shaft.  Not an easy fix but after a lot of bad language I was able to reinstall with a new screw.  The engine would not start.  It would try but just would not run.  I checked the compression and it was zero.  Pulled the head and discovered the intake valve was not closing completely.  Exhaust was OK but probably doesn't have enough clearance.  These valves are adjusted by filing/grinding the valve stem.  Not a big deal but I can not figure out why the valve clearance would decrease.  I can't imagine there can be enough valve/seat ware to reduce clearance nor the valve stem growing longer so what am I missing?  

Gary

Renton, WA




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