I have a '70 Mach 1 with a 351C-4V and have noticed a little tapping on the passenger side from just under the valve cover. A guy that is big on muscle cars told me it was a rocker arm tapping and to tighten it down. Do I just tighten the bolt in the center of the rocker down (I already have the valve cover off)..how much do I tighten it? I really need help because we are having a car show and cruise tomorrow at noon. Thanks for ANY help!