1942 - 1947 Chevrolet Shop Manual



	*6-23*

	The clearances that must be maintained between the intake valve stem and guide is .001" to .003", and the clearance between the exhaust valve stem and guide is .002" to .004". Quite naturally, if the valve guides are worn they should be replaced. To remove them from the cylinder head, the driver shown in Fig. 47 must be used. Place the cylinder head in an arbor press and press the guide from it using this tool. The valve guides do not have a shoulder to determine the distance they should be pressed into the cylinder head. The intake guides should extend above the cylinder head 1-1/16" while the exhaust guides extend above the head 61/64". These dimensions are very important, Fig. 48. To simplify this operation and make sure the valve guides are pressed in the proper distance, two valve guide drivers are available. These drivers contain stop collars to automatically stop the guides at the proper height. After the guides have been pressed into the cylinder head, they should be rough reamed with a .341" reamer and then finish reamed with a .343" reamer.
		Fig. 49—Valve Spring Tension Gauge of an engine are reconditioned or ground, the valve springs should be checked to be sure they have not been weakened from the heat of the engine. This can easily be done by placing the valve spring in the valve tester, U15, Fig. 49. and compressing it to a length of 1-1/2". At this length the spring tension should be from 125 to 133 pounds. Springs that do not test within these limits should be replaced with new genuine Chevrolet valve springs.



	Fig. 48—Valve Guides Valves and valve guides used on the 1942 engines are interchangeable with those on 1941 engines BUT NOT WITH ANY MODELS PRIOR TO 1941. VALVE SPRINGS, CAPS AND COVERS Genuine Chevrolet valve springs are made from a special analysis steel wire. They are accurately coiled, and, after being made, each spring is checked to insure that it is within the- limits for tension. Springs that fail to pass this inspection are immediately scrapped. Weak valve springs affect the economy and power of the engine; therefore, each time the valves	Fig. 50—Valve Spring Compressor Each valve spring is retained to the valve with a cap and key. It is necessary to compress the spring with the spring compressor. Fig. 50, which is a part of the cylinder head holding fixture, far enough to allow the keys to be inserted around the valve stem. The valve springs are assembled with the close coiled end against the cylinder head. NOTE—Due to the difference in the recess depth, the round valve spring caps must be installed on the intake valves and the hexagonal caps on the exhaust valves. The intake valve spring cap covers must be installed on the ends of all intake valve stems.