Presumably we are talking 4 stroke? If so, none or the exhaust - it will be at the top of the compression or the exhaust stroke
Inlet valve is open when piston moves from top dead center to bottom dead center inlet valve open and provide proper amount of fuel and air to the cylinder.
It is when the number one cylinder has reached top dead center on the compression stroke.
take of driver side valve cover, so you can see the rocker arms move. Turn the engine while watching the intake valve rocker for number one cylinder move. When the intake valve has just closed you should be close to the balancers mark for top dead center. That is the top dead center mark you will be looking for when putting distributer and wires back on.
Each cylinder has a top dead center position.
That would be the top of the compression stroke on the number one cylinder.
Yes
The TDC is when the number one cylinder is at the top or top dead center of the compression.
To replace the valve stem seals with the head on you must bring each cylinder up to top dead center, pressurize the cylinder with an air chuck screwed into the spark plug hole. (this prevents the valves from dropping into the cylinder) Now the seals on that cylinder can be replaced. The process is repeated on each cylinder. Note: you must prevent the engine from rotating when the cylinder is pressurized.
if auto related it stands for top dead center and refers to the position of the crank in relation to the positon of the number one cylinder.
only one cylinder can be at top dead center (TDC) at a time, usually this is cylinder number one. remember: on 4-cycle engines each piston reaches the top of its stroke twice, once for ignition and once for exhaust.
You can do it on the car by pumping compressed air in to the cylinder (must be at TDC). The compressed air will keep the valves pushed up while you remove the valve springs. The downside to this that you will have to have a special tool to compress the valve springs to remove the keepers and you can only do 1 cylinder at a time because each piston must be at top dead center.
turn engine to top dead center on compression stroke then turn 1 quarter of an inch passed set at .005