alright i know how to set ignition timing but if u install high compression pistons how do u know what to set the timing at i know u will have to retard it but

 

if you install high c/r piston it doesn't necessary mean you need to retard the timing. it depends on many things. first ocatne of gas you're running, head design, overall fueling/ignition maps and much more.

timing should be set at the highest point without getting any pining or detonation, where is that you ask? that comes with tuning and your setup, experiment use your judgment.