Dont remember cyl nr,but the upper one on right side gets damn hot compared to the three others. I been told a time ago that bor and mount a nippel to let air pockets to get out,beacause this one doesnt have control-pee installed from factory,but the casting in blockside is ready to be borred so ill go a head and do that before i try this on water today or tomorrow,depends on trailer is avaliable,but now its ready and im exited for this one. motor is johnson 85esl73m,boat is 540cm silver viking sport.