76 Chrysler 45hp shearing key

[ENorth]

My 45hp Chrysler keeps shearing the flywheel key. Runs 5 to 10, minutes in water. Any ideas on cause and cure? Thanks

 

[jerryjerry05]

What tuorqe are you using?
85# is about what you need.

ANY???? backfiring, coughing, missing?
A tiny cough can shear the key.

Coughing: the air screw not set right, or it's sucking air somewhere??

 

[Jiggz]

As Jerry mentioned, improper flywheel torque is most likely the cause. Contrary to popular belief, the flywheel key is designed NOT to hold the flywheel but to mark the flywheel with #1 piston at TDC. What holds the flywheel in place is it's nut torqued against the conical shaft.

If after applying torque and key continues to be sheared, then check the centricity of the shaft.

 

[Nordin]

You have to "lap" the taper at the crank before you reassemble the flywheel.
Use fine valve grinding compound paste such as Carbo Runddum and lap the taper and flywheel.
The surface should be fine gray in color after lapping and the surface of flywheel and taper have a contact of 90%.

Torque the flywheel nut to 80 foot Pound.