Q. What about the care of the valves?
A. They seldom get out of order, but they do get dirty as a result of carbon collecting on the valve seats. These carbon deposits, by preventing proper closing of the valves, permit the gases under compression to escape, resulting in loss of power and uneven running of the motor. If, when turning the engine over slowly, there is lack of resistance in one or more cylinders, it is probable that the valves need regrinding. As the “life” of the engine depends largely upon the proper seating of the valves, it is necessary that they be ground occasionally.
Q. How are valves removed for grinding?
A. (1) Draining radiator; (2) remove cylinder head; (3) remove the two valve covers on the right side of the engine; (4) raise the valve spring with lifting tool and pull out the little pin under the valve seat. The valve may then be lifted out by the head, preparatory to grinding.
Q. How are valves ground?
A. For this work use a good grinding paste of ground glass and oil procurable from auto supply houses. A convenient way is to put a small amount in a suitable dish, adding a spoonful or two of kerosene and a few drops of lubricating oil to make a thin paste. Place the mixture sparingly on the bevel face of the valve. Put the valve in position on the valve seat, and rotate it back and forth (about a quarter turn) a few times with a Ford grinding tool. Then lift slightly from the seat, change the position and continue the rotation, and keep on repeating this operation until the bearing surface is bright and smooth. The valve should not be turned through a complete rotation, as this is apt to cause scratches running around the entire circumference of the valve and seat. When the grinding is completed the valve should be removed from the cylinder, thoroughly washed with kerosene, and the valve seat wiped out thoroughly. Extreme care should be taken that no abrasive substance gets into the cylinders or valve guides. This can be avoided if the grinding paste is applied sparingly on the bevel face of the valve. If the valve seat is worn badly or smeared, it is best to have it reseated with a valve seating tool. This operation requires considerable skill, and perhaps had better be done by an expert mechanic. Care should be exercised against making too deep a cut, necessitating the retiming of the valve.
Q. What should be done when the valves and push rods are worn?
A. When the valves and push rods become worn so as to leave too much play between them, thus reducing the lift of the valves and diminishing the power of the motor, it is best to replace the push rods with new ones. The clearance between the push rod and the valve stem should never be greater than 1⁄32″ nor less than 1⁄64″. If the clearance is greater, the valve will open late and close early, resulting in uneven running of the motor. If the clearance is less than 1⁄64″ there is danger of the valve remaining partially open all the time. If replacing the push rod does not give the proper clearance, the valve should also be replaced. We do not recommend drawing out the valve stem, as the operation required, and the price of a new part does not warrant the time and expense necessary to properly do the work.
Q. What about valve springs?
A. When the valves fail to seat themselves properly, there is a possibility that the springs may be weak or broken. A weak inlet spring would probably not affect the running of the engine, but weakness in the exhaust valve spring causes a very uneven action, which is difficult to locate. The symptoms are a lag in the engine due to the exhaust valve not closing instantaneously, and as a result a certain per cent. of the charge under compression escapes, greatly diminishing the force of the explosion. Weakness in a valve spring can usually be detected by the following method: Remove the plate which encloses them at the side of the cylinder and insert a screw driver between the coils of the spring while the engine is running. If the extra tension thus produced causes the engine to pick up speed, the spring is obviously weak and should be replaced by a new one.