Exhaust and intake valve springs for a doubled valve train can be replaced without having to remove the cylinder head of the car, which will take approximately two special tools and a source of compressed air. First, the spark plugs, the valve covers, the cams and the rockers must be taken out. Insert an adapter into the spark plug hole and attach an air hose to this end and the other end must be connected to a compressed air supply. Use compressed air on the cylinder to fix the valves in position against the effects of the liquid. Lightly strike the top of each valve spring retainer to free the valve keeper from the spring retainer Employing a valve-spring compressor, compress the valve spring and extract the keepers by means of needle-nose pliers or magnet. Take off the valve spring and the retainer with utmost care to avoid the pressure of lifting the valve, while the air pressure is still retaining it in the closed position. Take out the previous valve stem seals; it is possible to tell an intake seal from an exhaust seal by how they are designed, and round the upper part of the valve stem with a rubber band or tape to prevent it from falling into the combustion chamber once again, before relieving the air pressure . It is also advisable to examine the valve stem to see if it is damaged and in the process check if the stem binds in the guide. Vibration pressure is then applied to lock the valve back in place and a new valve stem seal is fitted for the intake as well as the exhaust valves without requiring the valve to be pressed up against the top guide. Place the spring and retainer over the valve pushing the assembly just enough to fit the keepers to it, If needed use a little grease to hold the keepers in place. Take the pressure off the spring tool and make sure that the keepers are in place, then detach the air hose and take of the adapter off the spark plug hole. Perform the same for the rest cylinders, and finally fit the rocker arm assemblies, the cam shafts, the timing chains, and the valve covers. Turn on the engine to look for such signs as oil dripping and strange noises, let the car run for at least five minutes then rev it up.
