(7) The desired stem clearance is 0.0015 inch for the intake valve, and 0.0045 inch for the exhaust valve.
(8) If the clearance is greater than 0.0026 inch for the intake valve and 0.0055 inch for the exhaust valve, the
valve guides must .be replaced.
d. Removal.
(1) Install the valve guide drift on the top of the valve guide and see that both are properly alined.
(2) Drive the valve guide down and out of the cylinder block.
(3) Clean the valve guide seat with cleaning solvent and blow dry with clean compressed air.
e. Installation.
(1) Start the valve guide in the valve guide seat with the tapered end up.
(2) Use the valve guide drift to drive the valve guide in place.
(3) The distance from the valve seat face to the top of the valve guide must be 1 15/32 inches for both intake
and exhaust valves.
(4) Install the valves (par. 136).
(5) Install the cylinder head (par. 135).
(6) Install the engine (par. 175).
177. Valve Seats
a. General. The exhaust valve seats are replaceable. The intake valve seat is not exposed to such high
temperatures and therefore is not replaceable. If the intake valve seat becomes badly damaged or cracked, the entire
cylinder block must be replaced.
b. Inspection. Inspect the valve seats for pitting, excessive or uneven wear, cracks, and damage. If the intake valve
seats cannot be repaired by grinding, replace the cylinder block. If the exhaust valve seat is cracked, damaged, or
warped, it must be replaced.
c. Removal.
(1) Remove the engine (par. 174).
(2) Remove the cylinder head (par. 135).
(3) Remove the valves (par. 136).
(4) Clean the valve seat insert thoroughly.
(5) Use a valve seat insert removing tool and be sure to follow manufacturer's instructions supplied with the
valve seat insert removing tool. Be careful not to damage the cylinder block. Remove the insert.
(6) Use a valve seat insert cutting tool and cut the counterbore 0.0035 inch smaller than the insert that is to be
installed. Use 0. inch oversize valve seat insert.
Note. A standard insert should never be used as a replacement as it will not remain tight in
service.
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