Page:Popular Science Monthly Volume 88.djvu/157

 Overhauling Your Car for the Winter

By Victor Page {Continued from the December Number)

��Valve Removal and Inspection

ONE of the most important parts of the gasoUne engine and one that requires frequent inspection and refitting to keep in condition is the mushroom or poppet valve that controls the inlet and exhaust gas flow. In over- hauling it is essential that these valves be removed from their seatings and ex- amined carefully for various defects which will be enumerated at proper time. The valves are held against the seating in the cylinder by a coil spring which exerts its pressure on the cylinder casting at the upper end and against a suitable collar held by a key at the lower end of the valve stem. In order to re- move the valve it is necessary to first

��compress the spring by raising the collar and pulling the retaining key out of the valve stem. Many forms of valve spring lifters have been designed to permit ready removal of the valves.

When the cylinder is of the valve in- the-head form, the method of valve re- moval will depend entirely upon the sys- tem of cylinder construction followed.

In the Franklin engine, which is shown in part section at Fig. 9, it is not pos- sible to remove the valves without taking the cylinder ofif of the crank case, be- cause the valve seats are machined di- rectly in the cylinder head and the valve domes are cast integrally with the cyl- inder. This means that if the valves need grinding the cylinder must be removed

��Vd/ve Springs Valve Stem Guides Vdive Operating Rods

��yalveb-

��Cylinder

��Camshaft

���Fig. 9. A sectional view of part of the Franklin motor, showing valve seats machined directly in cylinder head, and valve domes cast integrally with the cylinder

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