In regards to the carb. leak I am blank but as to the issue of snapping off studs, This can only be caused by your motor not being mounted properly and having weak studs. If you use something between the frame and the mount it is still moving regardless of how slight. When theses engines are mounted securely to the frame, as designed the motor vibrates with the frame. So it is not suggested to do so. just make sure the back mount is securely mounted, and modify the front mount as necessary.