Great Plains Logo & Address


The kit consists of:
1 each magneto housing adapter
1 each mag drive puck
1 each flywheel end piece
1 each mag drive hub
3 each short allen head screws
4 each long allen head screws

Bolt case together with a couple of the large case nuts. Place mag housing adapter against the case. It will probably have some slight rock to it. If so take a file and slightly taper the centering boss on the mag housing until it fits without rocking.

With housing fitting squarely against the case, the two threaded holes for the magneto should be at 9:00 and 3:00. The four smaller holes in the mag housing are pre drilled for a number 21 drill bit. This is the tap size for a 10/32 thread. Drill and tap one hole at time. When completed with 1st hole, drill the mag housing out for the allen head screw and install screw before going to next hole. Repeat until all four holes are done. Drill and tap into the case about 3/4".

Note: It may be necessary to slightly file the area behind the allen head screws so that they sit flush on the surface and screw in easily.

Place flywheel end piece on crankshaft and tighten nut. Note: Only one dowel pin is used. With a piece of angle iron with a 5/16" hole in it, hold the prop hub. Now tighten the flywheel gland nut up to 100 ft. Lbs. (With case halves together.) Remove case half and check end play with feeler gauge. .004" to .006" is what you want. Measure total end play, subtract .004" and this number is what you are looking for in total shim thickness. It may take 2 or 3 shims.

With end play set install shims and flywheel end piece. Torque to 140 ft. Lbs. Use Locktite (blue). Set engine so #1 cylinder (right front) is set at 28 degrees BTDC (before top dead center). Install mag drive hub so that drive tangs are at 1:00 and 7:00. Install 3 allen head screws with lock washers.

Install mag drive puck and magneto. If mag will not seat against the housing, use a belt sander and sand off mag side of mag drive puck. You can also use a mag gasket between mag and mag housing.

Go back to Mag Housing Order Info

Go back Shopping Cart Index

Go back to Instruction Index