I have a 5hp Briggs that runs great but has a tendency to shear the shaft key.
It is a horizontal shaft engine on a leaf vac. The data plate is gone so I do not know the engine model. This was not a problem until I replaced the block. Since then it will run for about a minute then the key shears.
Any help would be appreciated. Thanks.
Jim

Is it possible you are not seating the flywheel and flywheel key properly before you torque it down. I think torque is 55 ftlb. Have a good one. Geo

Make sure the flywheel is properly torqued as per geo's post, also make sure the vacuum impeller is also torqued down good. If either of these are loose, it can cause the flywheel key to shear.

Thank you for the input. I will recheck the torque. I was running the engine with out the impeller installed. Would this have an impact?

Thank you for the input. I will recheck the torque. I was running the engine with out the impeller installed. Would this have an impact?
The impeller works as a counter balance to give the engine some extra inertia, since ignition timing is slightly advanced, this could help cause the flywheel key to shear when trying to start, particularly if the flywheel is not tight enough.

I installed the impeller and that solved the problem. Thanks for the help.
Now it runs great but now it won't start unless I prime the carb. Oh well just makes life interesting another problem to solve.:wave: