1973 Evinrude Norseman 40 HP Service Manual, Page 39Get this manual
DESCRIPTION The power head consists of the cylinders, pistons, rods, crankshaft, and crankcaseThe power head has two horizontally mounted cylindersAlternate firing order is used so that each cylinder delivers one power impulse per crankshaft revolutionSee Figures 5-1 and 5-2
EXHAUST PORT EXHAUST GASES