Going back together with the 454 mercruiser. Need to adjust the hydraulic valves, with the motor not running. Once the exhaust manifold back on cannot get valve cover off. Head on and intake still off. Was thinking install the intake. Bring the piston up to firing position by watching the firing order at the distributor, tighten the rocker till play out of rod plus ½ turn. Will this work or are there better ways?