firing order 1 5 3 6 2 4 if a 6 cylinder or 1 3 4 2 for a 4 cylinder, turn off ignition, hand turn engine using front pulley or flywheel teeth (apeture in housing) rocker cover off, engine cold, 13 thousanths of an inch clearance for inlet and exhaust, adjust the opposite cylinder to the one firing ie adjust no2 if no5 rocker arms are both moving ie closing and opening and vica versa, recheck after a few hundred miles
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix lorries/trucks.