Specifically, use TDC on the compression stroke. Near the time the plug fires off.When properly adjusting valves spark plugs should be removed so pencil etc. can be inserted into spark plug hole touching top of piston while rotating top screen clockwise until TDC { piston is at top dead center } can be located at top of stroke & both intake & exhaust valves are closed & both rocker arms are loose. Adjust intake & exhaust valves per specs. in Engine Manual. Engine should be cold when adjusting valves. On twin cylinder engine move to opposite side & rotate engine clockwise after inserting pencil into spark plug hole until TDC is reached. On B&S engines manuals state 1/4" past TDC. A slight drag should be felt when inserting feeler gauge between rocker arm & push rod. Recheck with feeler gauge after torqueing jam nuts per specs. in manual.
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