move each cam a little,then move the crank untill all marks line up,hint---youll need some help holding the cams still,use a pair of drill bits through the cam caps,when the timing belt is on and you release the tensioner,then pull the drill bits out and rotate the egine by hand to re-check your marks,,,last hint---remove number one spark plug to look down and check for TDC to find the correct mark,----LS motors arent interference at low rpms,DOHC motors are interference only when V-TEC is engaged,good luck and post your results