1967 Evinrude StarFlite 80 HP Outboards Service Manual, PN 4359, Page 43Get this manual
DESCRIPTION The power head consists of the cylinders, pistons, connecting rods, crankshaft, and crankcase The power head has two banks of horizontally-mounted cylinders inV" formation 90 apartThe firing order is combined so that each cylinder de livers one power impulse per crankshaft evolution, thus giving one power impulse at every 90 degrees of crankshaft rotationSee Figur 5-1CRANKCASE AND CYLINDERS To provide equal fuel vapor distribution to the four cylinders, the crankcase is divided into four equal areas, and each is sealed off from the others through the use of compression type ealing rings on the crankshaft webs All four crankcase distribution chambers must be isolat ed from each other at ll times to prevent compression leakage between cylinders See Figure 5-1CYLINDER HEADS There are separate cylinder heads for each bank of cylindersThe cylinder head covers are numbered to corr espond to the ignition firing orderTh starboard cy linde head cover is numbe ed upper nd lower and the port cylinder head cover is numbered upper and lowerPISTONS The pistonswith the piston rings, receive the forc of combustion in the cylinder head, so it is necessary tha both the pistons and piston rings be pr oper ly fitted to form seal between the piston head nd cylinder wallsTo retain maximum power within the cylinder above th piston head, the cylinder must be perfectly ound and the piston rings correctly seated in their grooves FUELINT AKE AND EXHAUST CYL NDER NO1 EXHA UST EXHAUST MAN FOLD