Ignition Timing IAT compensation

Hi

I have my timing set up with 30c IAT which I was able to run the tests at, what would be a good step to retard timing, let's say I would want to retard timing every 10c the IAT rises, what retard factor would you recommend?

Why don't you start with 0.5 deg for each 10degC change. Do you have knock control? If so, the presence of knock at elevated IAT could give you a clue to the required ignition change to avoid the knock.