i got a junk engine with the piston stopper screwed in but when attempting to loosen the two clutch hex bolts the clutch spins , i guess the engine is rubbish.
big block engines, 3.4cc/.30ci and higher, have a sort of friction clip that holds the flywheel. When partially unscrewed, this means that thd friction is no longer holding it together, allowing thd flywheel to slip.
That's very normal The flywheel is attached to the piston rod as seen from the video, but you can try to completely unscrew the clutch and you'll see that it's only held together because of friction. Use loctite when reassembling the clutch, and screw it in very hard, to prevent it from slipping like it currently is
i removed the worn clutch pads from my zenoah boat engine with the piston stopper in and i wanted to use the the pads from the HY engine but since the clutch pads hex bolts are so tight the only way i can see removing them without spinning is to clamp the pads but i'm not spending any more time with the HY engine i can buy new pads for like $12 also the HY flywheel/fan locking key is broken.