Do a search there is alot on this.. What thermo are you using.. Did you get all the air out of the system?? Fans turning the right way how big and what air volume do they move.. What turns on/off fans and at what temps.. If using puller fan is it shrouded.. What mixture are you running in radiator.. Were is your timing.. are you running lean.. Water pump pumping/moving water.. Belt tight.. What else is piled up in front of radiator, coolers,custom grill, lights, plate ..