Assembling your snowblower engine after repairs are done is a chore that requires a good amount of detailed work to be done correctly. There are a number of steps to follow before you are outside chasing snow.
Step 1 - Replace Oil Seals
Replace the oil seals by pressing them straight into the seat and securing them by tapping with a block wood and rubber mallet.
Step 2 - Attach Breather
Attach the breather making sure it is assembled with a valve plate, spring, gasket, and cover.
Step 3 - Compress Valve
Fully compress the valve spring for the intake valve and install it with any washers and retaining clips. Repeat for the exhaust valve and then install the valve cover.
Step 4 - Use Piston Rings
Make use of a piston ring expander if available or use your hands to expand the valve rings and slip these over the pistons placing them in the proper grooves. Avoid scratching the pistons and do not expand the rings more than needed. If installing new rings, deglaze the cylinder wall with a fine emery cloth using diagonal strokes. Clean away any debris created deglazing.
Step 5 - Place Piston Pin
Place a couple of drops of oil on the piston pin, position the rod, and slide the pin in place. Tap it with a press if tight. Use a new clip to secure the pin.
Step 6 - Place Crankshaft
Place the crankcase flywheel/magneto on top of some wood blocks so when installing the crankshaft it will be off the table. Use a rotating motion to insert the crankshaft into the flywheel/magneto end bearing making sure to apply some engine oil for lubrication.
Coat the piston with oil and orient the piston so you gap the rings from top to bottom at 45, 135, and 225 degrees. Tighten to fully compressed and release just a bit. Position the piston in the correct orientation to the rod and gently tap into place with a rubber mallet.
Coat the crank pin journal with oil and position it and the rod bearing so they make contact. Hand thread the locking nuts and bolts. Then use a torque wrench to tighten these to the proper toque listed in your owner’s manual. This is the most critical part of the engine assembly.
Step 7 - Install Valve Filters
Install all valve filters in their designated holes
Step 8 - Rotate Camshaft
Rotate the crankshaft until the timing marks line up with the camshaft bearing. Slip the cam gear so the timing marks line up exactly.
Step 9 - Install Oil Pump
Install the oil pump. It is in two pieces and the flat parts face out. Then install the crankshaft/oil sump cover.
Step 10 - Test Rotation
Test the crankshaft rotation by grasping it and making two complete revolutions. There should be no binding and the pistons should bob up and down freely.
Step 11 - Install Cylinder Head
Place a new gasket along the head and install it with bolts making them finger tight. Place the gasket cover on and tighten.
Step 12 - Install Ignition System
Set the proper gap before installing the ignition system.
Step 13 - Install the Flywheel
Install the flywheel and tighten with the torque wrench according to instructions.
Step 14 - Install Spark Plug
Install a new spark plug with washer by first threading by hand and then tighten to specifications — usually 15 to 30-foot pounds.
Step 15 - Install Muffler and Carburetor
Install the engine muffler and carburetor making sure to tighten the carburetor the proper torque, 6 to 8-foot pounds. Once all engine parts are assembled, install the engine on the snowblower assembly.