Small Engines (Lawn Mowers, etc.): Briggs L head/twin 18HP valve lash setting procedure, carbon buildup, engine noise

Question
John,

I have a 422707 Briggs and can hear the valves clicking.  How do I set the lash?  Thanks in advance. Steve

Answer
  The procedure for an L-head is pretty involved, and would require removing valves and grinding the stems, and that is not likely the problem.  These engines have a carbon buildup thing, that is likely the cause of your noise.  I have heard of techs pulling an engine
for engine noise, looking for a loose rod, and it was just a
buildup of carbon in the cumbustion chamber, so just pull the heads and give a good scraping, and try to save the gaskets, many times they can be reused.  Try this first, and let me know.  you will
also note it will crank easier as well.