CAUTION: The following procedure assumes that the spark plug wires and distributor (if equipped) are installed properly. If you are trying to determine TDC for proper distributor installation, piston position can be determined by feeling the compression in the spark plug hole of cylinder number one and then aligning the timing marks.
Top dead center (TDC) is the highest position in the cylinder that each piston reaches as it moves up and down as the crankshaft rotates. Each piston reaches TDC during the compression cycle and again during the exhaust cycle, but TDC usually refers to the piston's position during the compression cycle.
Setting the piston to TDC is an important part of many processes, such as removing the camshaft and drive belt or removing the distributor (if equipped).
Before starting the process, make sure that the transmission (gearbox) is in neutral. Apply the handbrake or block the rear wheels. Disable the ignition system by disconnecting the coil high-tension wire from the center contact of the distributor cap/diagnostic connector and ground it to the block using an auxiliary wire. Remove the spark plugs.
To set the piston to TDC, rotate the crankshaft using one of the methods described below.
CAUTION: When looking at the front of the engine, the crankshaft should rotate normally clockwise.
(Original source of information MitsubishiMan)
The most preferred method of turning the crankshaft is to use a socket wrench.
If you can use the help of an assistant who will turn the ignition key to the "start" position for short periods of time, then it is quite possible to bring the piston closer to the position.
Make sure the assistant is out of the vehicle and does not touch the ignition switch, then use the key.
Mark the position of the high voltage path terminal for the No.1 spark plug on the distributor cap. If this terminal is not marked, trace the wire path from the No.1 spark plug to the distributor cap.
Mark the distributor housing directly below the contact.
Remove the cover from the distributor and set it aside.
Locate the marks on the front cover You will see the marks directly above the crankshaft pulley. Rotate the crankshaft so that the mark on the front cover matches the mark on the pulley.
Once the piston of the first cylinder has been set to the TDC position of the compression cycle, the TDC position for the remaining cylinders can be determined by turning the crankshaft and following the firing order.