IO-390-D Series Engine Maintenance Manual
72-30
© 2020 Avco Corporation. All Rights Reserved
Page 202
March 2020
IO-390-D Series Engine Maintenance Manual
(11)
Install the Gage (ST-310) on the valve on the cylinder head as shown in Figure 6.
(12)
Tighten the cap screws (identified in Figure 6) equally. If the casting touches the lower
cap screw, put the washer under the head.
(13)
Measure stem movements by moving the valve stem along the valve guide wear line
(inside diameter of the valve guide, parallel to the centerline of the valve rocker arm).
Figure 6
Gage ST-310 Installation on the Cylinder Head
(14)
Install the Gage Adapter (ST-310-9) over
the top of the valve stem (Figure 7). Make
sure it is tight.
NOTICE:
If you can move the Gage
Adapter (ST-310-9) on the valve
stem with your hand, it is
incorrectly installed.
(15)
Push the valve stem and Gage Adapter
(ST-310-9), against the upper exhaust
valve spring seat as far as they will go.
(16)
Put the blade of a screwdriver in the area
between the exhaust valve spring and
Gage (ST-310).
Figure 7
Gage Adapter (ST-310-9)
Assembled on Exhaust System
(17)
Use the screwdriver to push the
valve and adapter the maximum
distance away from the dial
indicator as shown in Figure 8.
(18)
Move the dial indicator toward
the adapter post until the
indicator is preloaded
approximately 0.010 in. (0.254
mm), and lock it in place with
the set screw.
(19)
Adjust the dial of the indicator to
read "0" (zero).
Figure 8
Dial Indicator
