Disassembly

IGNITION SYSTEM

Ignition Harness. Remove the terminals from the top and bottom spark plug. Detach all clips, clamps and grommet plates securing the leads to the engine. The ignition harness on the dual magneto cannot be removed from the magneto without removing the cover from the magneto.
NOTE
Before detaching clamps, clips, grommet plates etc., mark the location of each. Differences in various installations make it impossible for this manual to point out the correct attaching points.
Magneto- Loosen and remove the two 5/16-18 nuts,lockwasher and clamps which hold the magneto to engine. Remove magneto and harness from the engine.


CYLINDERS, PISTONS AND VALVE TRAIN

It is assumed that the ignition harness, intake pipes and primer lines have been previously removed. Intercylinder Baffles. (where applicable) Using the intercylinder baffle tool (64885), release the baffle retaining hook so that it disengages the retainer. Remove the intercylinder baffle and hook from between the cylinders.Oil Drain Tubes. Loosen hose clamps at lower end of tube and slide tube out of hose. Loosen gland nut at cylinder head fitting and remove drain tube.Cylinder. Remove the rocker box cover and gaskets.Rotate the crankshaft to place the piston of no. 1 cylinder at top center of the compression stroke. This will place the valves in closed position and the piston extended away from the crankcase to avoid damage when cylinder is removed. Remove the 5/16-24 self-locking nut from the valve rocker fulcrum . Remove the valve rocker arms and fulcrum from cylinder. Remove the square washers from the stud. Remove the push rods by grasping the end and pulling through the shroud tube. Remove the 1/4-20 plain nut , lockplate and spring . Pull shroud tubes out through the cylinder head and discard the shroud tube seals.
Remove the cylinder base hold-down nuts; then remove the cylinder by pulling straight away from the crankcase. As the cylinder is pulled away, catch and hold the piston to prevent it from falling against the crankcase and being damaged. Discard the cylinder base oil seal rings.Pistons. Remove piston pin plugs from the piston. Using a piston pin puller (64843), pull pin from piston and remove piston.
CAUTION-
After the removal of a cylinder and piston the connecting rod must be supported to prevent damage to the rod and crankcase. This is done by supporting each connecting rod with torque hold down plate ST-222, rubber band (discarded cylinder base on seal rings) looped around the cylinder base studs
Removal of the other cylinders and pistons may be done in any desired order, but less turning of the crankshaft is involved if the cylinders are removed successively in the engine's firing order 1-3-2-4. Left hand rotation firing order 1-4-2-3. Hydraulic Lifters. Remove the hydraulic lifter from the crankcase. Place each lifter as removed from crankcase in its proper location in the cleaning basket. The hydraulic lifters must be replaced in the same location in crankcase from which they were removed.
Cylinders- Place cylinder over the cylinder holding block (64526-2), assemble valve spring compressor (ST-419) on cylinder, and compress valve springs far enough to remove the valve retaining keys.
NOTE-
If keys are stuck tight in spring seat, a light blow with a leather mallet on top of compressor will release keys. Remove all valve spring seats and springs from rocker box, keeping parts for each valve separate. Hold valves by the stem to keep them from dropping out of the cylinder, and remove cylinder from holding block. Now reach inside of cylinder and remove valves. If difficulty is experienced in pulling the tops of the valve stems through the valve guides, push the valves back in position and clean the carbon from the stems.





OIL SUMP AND FUEL INDUCTION

Intake Pipes.
Loosen and remove the capscrews that attach the intake pipe flange to the cylinder head intake port. Loosen the hose clamps and slide the pipe off the sump connector. Mark the intake pipes as they are removed from the engine so that they may be reassembled in the same location.

Carburetor.
Remove the carburetor from the mounting pad of the sump.
Oil Suction Screen.
Unscrew the hex head plug and remove gasket and suction screen.
Oil Sump.
Remove the fastenings from the periphery of the sump and remove the sump.



CRANKCASE, CRANKSHAFT & RECIPROCATING PARTS

Remove the oil pump and vacuum pump body assembly by removing the four plain nuts, lockwashers
and plain washers. Discard the "o" rings seal and oil seal in pump body. Remove the driven impeller from the crankcase and the driving impeller from the pump shaft.
The oil pump shaft cannot be removed until the crankcase is parted.Remove the oil pressure screen housing and the oil cooler adapter or the oil filter adapter assembly (where applicable) from crankcase. Remove the oil cooler adapter from the oil filter adapter. Remove the oil filter and adapter plate. Also remove thermostatic oil by-pass valve. Discard all gaskets.
Remove the oil relief valve plug, gasket, spring and ball from the crankcase.
Remove the oil filler tube.
Remove the nuts and bolts from the parting surface of the crankcase, which hold the crankcase halves together.
Remove the crankcase from the overhauls stand and place on the work bench.
Remove the starter ring gear support assembly from the crankshaft propeller flange by tapping lightly on the rear of the assembly. The alternator drive belt will be removed with this unit.
Remove the external retaining ring , seal retainer and "o" ring seal from the tachometer drive
adapter. The tachometer drive adapter can not be removed until the crankcase is separated.
On engines equipped with a governor drive, remove the governor drive cover, "o" ring, and governor
drive thrust washer, from the nose of the crankcase.

The crankcase may be separated by first resting on the bottom of crankcase and gently tapping with a soft hammer the thru-studs on the loose ends until the crankcase begins to separate. Place the crankcase on the left side and continue to remove the right half of crankcase. Reach down through the cylinder pads and push the crankshaft bearing insert down on the crankshaft, so they will not fall when crankcase half is removed. Separate the crankcase by hand and remove the bearing inserts and crankshaft assembly.
Remove the camshaft, tachometer drive adapter and the crankcase breather baffle. Engines equipped with a propeller governor it is necessary to remove the governor drive gear at the time the camshaft is removed. Also remove the governor drive shaftgear from the right half of the crankcase.



Camshaft.
Remove the camshaft gear and the tachometer shaft.
Remove the oil and vacuum pump drive shaft by removing the nut and lockplate. Use service tool ST-416 to turn pump shaft while holding nut with open end wrench. Remove oil pump drive gear. Remove drive shaft from crankcase.
Crankshaft.
With the crankshaft properly supported at front and rear main bearings, remove the nuts securing the rod caps to the connecting rod.
Remove the rods by tapping on the rod bolts with a soft hammer. Discard the bearing inserts, bolts and nuts. Reassemble each cap with its corresponding rod. Rods and caps are not interchangeable.
Remove the crankshaft oil seal and the expansion plug from the crankshaft. Do not remove the propeller flange bushings from the flange of the crankshaft unless they are damaged and/or loose.







Counterweights.
Counterweights are disassembled from the crankshaft merely by removing the retaining rings, after which the washers ,rollers and counterweights may be removed from the crankshaft ear.
To remove the crankshaft gear flatten out the lockplate and remove the hex head screw or screws
Tap the crankshaft gear gently with a fibre drift to remove gear from crankshaft. Do not remove the dowel from rear of crankshaft ““less it has been obviously damaged.