Engine timing

Hello. I have a Mazda Allegro 1998 with a 1.8L engine, automatic 106.000 miles. I decided to take off the cylinder and have it serviced. I serviced the fuel injectors and changed filters. Before the extraction of the cylinder head the compression at each cyclinder was 160 - 170.

Once assebled the cylinder head again, the engine know hesitates at idle and turns off, cant sustain the a/c and the compression has gone down to 120. Can the sole cleaning of the carbon deposits in the pistons and the cylinder head cause such a drop in compression? Could this be bad timing of the engine? Once the cylinder No. 1 is at TDB how should the intake and exhaust cams be pointing?
Thank you.