The springs are located on top of the valves, under the valve cover. Their main purpose is to provide tension on the valves and keep a tight seal on them inside the combustion chamber. If a spring is weak or broken, the combustion chamber will not have enough compression, and this will result in a loss of power. Weak valve springs will typically cause a misfire and a loss of power as engine speed increases. The engine may start, and run effectively up to 4000 RPMs, but at higher speeds it may misfire. This will result in a loss of power, as the valves are floating because of weak springs, and they are unable to keep up with the speed of the valve train. To check the condition of these springs, remove the valve cover and inspect the springs. If you notice a broken spring, then you will have to...
The springs are located on top of the valves, under the valve cover. Their main purpose is to provide tension on the valves and keep a tight seal on them inside the combustion chamber. If a spring is weak or broken, the combustion chamber will not have enough compression, and this will result in a loss of power. Weak valve springs will typically cause a misfire and a loss of power as engine speed increases. The engine may start, and run effectively up to 4000 RPMs, but at higher speeds it may misfire. This will result in a loss of power, as the valves are floating because of weak springs, and they are unable to keep up with the speed of the valve train. To check the condition of these springs, remove the valve cover and inspect the springs. If you notice a broken spring, then you will have to remove and replace it. To replace a broken or weak spring you will need to remove the carburetor, muffler and valve cover from the engine, and remove the spark plug from the cylinder head. Rotate the piston to top dead center making sure the magnets on the flywheel are in line with the ignition coil. Next, remove the jam nuts securing the rocker arms, and disconnect the rocker arm pivots and the arms. Remove the push rods and the rocker arm studs, then pull out the guide plate. Next, remove the cylinder head bolts in a diagonal pattern so you do not warp the cylinder head, then place the cylinder head on a bench. Use pliers to remove the valve spring retainers and the springs. Take some fine valve lapping compound and apply it to the valve seat and cylinder head. This will help them seat properly. Insert the valves into the head and use a lapping tool to seat them by rotating the lapping tool in your hands. Next, remove the valves and clean the lapping compound off the valve and cylinder head. Lubricate the valve stems with clean engine oil and insert them into the cylinder head. Install the new seal on valve then install the spring and retainer locking it into position on the valve. Clean the surfaces for the new head gasket and re-install the cylinder head back onto the engine. Tighten the bolts down in an alternating pattern to avoid warping the cylinder head. Next, re-install the guide plate and rocker arms studs, then torque down to manufacturer’s specifications. Then, insert the push rod, slide on the rocker arms, and thread the pivots loosely. Use a feeler gauge to gap the rocker arms 3 to 5 thousandths of an inch from the valves. Thread the jam nuts and tighten them down, then re-install the spark plug. Reinstall the carburetor, muffler, and valve cover gasket, then re-install the valve cover. Tighten the bolts in an alternating pattern to manufacturer’s specifications.
Read More