Sorry your incorrect. It's the resistance of the cam and valve train, that keep any slack being introduced into the drive side of the cam chain, in a SBC V8. If the cam was to keep more momentum than the crank at deceleration( try to spin faster than the crank) and effect cam timing then it would be a mute point because your not under power. Also who's to say that the spring in the tensioner would be able to resist that force anyway.....