I had a block crack recently but the cam looks to have broken first then wedged in the crank bending the rod. I have a good flywheel head intake and carb now. Bought as a spare here off Bobs and this was the first time running it. Guessing it was maybe from someone twisting the cam because it broke right at the sharp corner where the stem meets the cam gear. Split the block where the cam inserts on the flywheel side all the way up the cylinder.