Engine Assembly

The clearances that must be maintained between the intake valve stem and their guides is .001" to .003" and the clearance between the exhaust valve stems and their guides is .002" to .004"

Valve Guide Remover and Inserter

Quite naturally, if the valve guides are worn, they should be replaced. To remove them from the cylinder head, the driver shown in Fig. 61 must be used. The cylinder head is placed in an arbor press and the guide pressed from it, using this tool.
In replacing the valve guides, the valve guide collar is assembled to the valve guide with the open face towards the cylinder head on the exhaust valves and the intake valve spring is assembled to the guide with the open end up. See Fig. 65. The valve guides are then pressed into position, with the
COLLAR COLLAR

Fig. 65— Valve Guides and Spring Seats
special driver shown in Fig. 64, on an arbor press until the shoulder on the guide is flush with the cylinder head.
Genuine Chevrolet valve guides, as sold through the parts department, are rough reamed. Whenever new valve guides have been installed, it is necessary to ream them to size with the pilot reamer shown in Fig. 66, which is .343" in size.
ing which is used to direct a single stream of water to the single exhaust valves at the end cylinders and the other with two openings which direct two streams of water to the other exhaust valves. See Fig. 62.

Grinding Valves

There is no operation, in the maintenance of an automobile that is more important than the valve grinding operation from the standpoint of engine economy and performance.
Extreme care should therefore be used when-ever valves are ground to maintain factory limits and clearances, as only by maintaining these limits and clearances can one expect to get good engine economy and performance.
After the cylinder head has been removed from the engine, and all of the parts disassembled from it, all carbon should be thoroughly cleaned from the combustion chamber, valve ports and guides, and the head thoroughly washed.
Cylinder Holding Fixture
The valve heads set down in pockets in the cylinder head, and this construction necessitates
Fig. 63— Cylinder Head Holding Fixture
the use of a cylinder head holding fixture combined with a valve spring compressor, see Fig. 63, for the removal of valve springs and the grinding of valves.
Valve Guides
The clearance between the valve guides and the valve stems is very important. Lack of power and noisy valves, in many instances, can be traced to worn valve guides.
The intake valve guides should be checked with a new intake valve and the exhaust valve guides should be checked with a new exhaust valve, because the diameters of the stems are different on these parts.

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