787 rotary valve damage

[DnE1800twin]

I have a 787. last yr a carb bolt vibrated loose and damaged the rotary valve. i took the motor apart to et the bolt out. ive gone thru 4 rotary valves since then. Like something is catching the leading edge. what could keep causing this? Do the pistons create a dramatic pressure in the crankcase that would blow the valve out enuff to catch on the lip of the valve cover??

 

[El Toro 33809]

Had a carb bolt do this to our 96 GTI. It damaged the gear on the rotary valve shaft and displaced the gear on the crank. After a rebuild we haven't had any trouble. Is the area where the plate turns completely smooth so nothing can hang up?

 

[brock1]

how much play (clearance) do you have on the rv have you checked it?

 

[DnE1800twin]

There is a little play between the block and cover plate. not enuff to warrant this kind of damage. the surface is s
Smooth. there is a very shallow groove about 2 inches long in an arc from the damaged RV. IVe already replaced the top end. does anyone sell a rebuilt bottom end?