Hello everyone! I've disassembled my CVH 1.6 (with Hemi (89SM) head) engine. So i decided to tune head: to lighten valves, to make chamfer 30* and to polish the head for compression improvement. But there are some questions - how to measure compression ratio? how to calculate what compression rate is needed? because the piston is with displacer and i am not sure if my cylinder head wasnt polished before.... how to define it? Thanks for your answers.