camshaft. So far no issues. However before I dis-assembled the heads I did measure the clearance between the camshaft lobes and the lifter and used this measurement for comparison after the new lifer installation. I didn't notice any difference and if I understand correctly that since the lifters are hydraulic they will compensate for miniminal lash (wear), thus no adjustments required. Obviously if there are excessive wear marks on the camshaft I would replace it as well. I am not an expert but that is what I did. I also used aftermarket ITM lifters that were half the price only after my original lifters failed after I refurbished them (definitely my mistake). Just wished I had done this originally as it was easier with the engine out of the car but at the time I was trying to save money after a costly rebuild and upgrading everything! I did search the forums and there is a lot of good information available. Hope this helps and good luck. Cheers,