Originally Posted by ozmoses
Think of the valve as, well, a valve or perhaps a door. Open is open, closed is closed.
Opens into combustion chamber. Closes at (in) the head.
Take a length of coat hanger, or stiff wire & insert into the spark plug hole; as the piston rise in the bore it will push the wire ahead of it. When it stops pushing, this is TDC for that particular cylinder.
But it HAS to be TDC on the compression stroke
, NOT on the exhaust stroke
. Any ole TDC won't work...