retard timing

i need to retard my base timing a littel for about 7-8 psi and i dont have a timing light that will tell me right were im at. if i retard it 4 deg. will i stll be between the timing maks? how much of a turn is that?
and do i turn it tords the front of the car or the back?

why do u need to retard your timing? If you are detonating at that level of boost is isnt from that. If you still have the stock heat range plugs you should change those and thatll help (NGK BKR7E). Also make sure you are getting enough fuel. But retarding your timing will just hurt your drivability and kill your gas mileage.