Need a head for B18 ASAP

[ViPER1313]

On the DSM when you line the cam's up at the position where all valves are closed they will simply sit in place because none of the cam lobes have any stress on them. You are right that at most places in the cam's rotation it will not simply sit there, but when none of the lobes are pressing against the rockers / valves, the cam is unstressed and will sit in place.