Sometimes, some are not aware that the no. 1 piston rises to the top twice whereby both times are not indicating the top dead center, (TDC) position.
1. If one's timing gear has a tiny indentation, or no indentation, to try to locate this indentation, first remove all four (4) spark plugs so the engine can rotate easily with a hand crank.
2. Next observe piston no.1 through spark plug hole no. 1, (closest to the radiator), to watch piston no. 1 as it rises to the top twice, one right after the other while slowly turning the hand crank.
3. Then, while holding one's finger over & sealing spark plug hole no. 1, one time just before no. 1 piston rises to the top, (the exhaust stroke), it will not compress air against your finger because the exhaust valve is open; but on the very next time it rises to the top, (the compression stroke), it will compress air against your finger because the intake valve & exhaust valves are both closed.
4. The time the piston rises towards the top "and" compresses air against your finger, i.e., (the compression stroke) is the time when the timing pin should slide in a recess in the timing gear as the piston reaches the top. This no. 1 piston position is known as top dead center, (TDC).
Hope this helps.