X flows timing is easly checked from start to finish,
Basics
The notch in the front pully is like a chisel mark not to worry there, No1 spark plug out long thin screw driver down bore bring piston to top dead centre, rocker cover off see if No 1 Rockers are top dead and No4 is rocking, that will inform you timing chain hasnt slipped.
That was my first thought: one link slip on the timing chain is about 20 degrees.
