copied from another thread:
Firing order on a xflow is 1243 which isn't a regular firing pattern. Most 4 cylinder engines are 1342.
1 is at the front, 4 is at the bulkhead.
There are two TDC's when lining up the marks on the front pulley and front cover. One for cylinder number 1 and one for cylinder number 4. You have to make sure that you have TDC on number 1 to set the timing. When looking for TDC on number 1 the valves need to be shut. At the same time you have number 1 cylinder firing cylinder number 4 piston will be at TDC with the valves open. The easiest way to check is to take the rocker cover off.
TDC on number 1 = valves shut and rockers NOT moving on number 1, and valves on number 4 moving.
TDC on number 4 = valves shut and rockers NOT moving on number 4, and valves on number 1 moving.