Pontiac Fiero 1988 Service Manual page 282

GENERAL ENGINE MECHANICAL 6A-5
G20008-6A
Figure 8 Checking Valve Spring Load
If valve stem seals are the
be sure they are properly
groove and not twisted.
Y R i n g t y p e
seated in the
1 - PUSH THE VALVE SEAL
SQUARELY ONTO THE
VALVE STEM UNTIL THE
VALVE STEM BOTTOMS
IN THE TOOL
2 - CHECK FOR BURF
3 - SEAL
4 - J-22315
Figure 9 Locating Valve Seal (Typical)
V A L V E INSTALLATION
There are several different methods of measuring
to determine correct valve installation after regrinding
valves or valve seats. Dimensional specifications in
specific engine section will indicate method to be used.
V A L V E S T E M HEIGHT (BRIDGE-TYPE TOOL)
Tool Required:
J 25289
m Installed valve stem height (Figure 10).
Excessive valve stem height is caused by
lowering of the valve seat and excessive
valve face grinding during reconditioning.
To correct, remove the valve and shorten
the valve stem by grinding. (Refer to Figure
11 for specifications.)
• Valve stem-to-rotator height (Figure 11)
N O T I C E :
If below specification (Figure 11), the
valve must be replaced to avoid interference of the
2.
3.
.015" MINIMUM BETWEEN VALVE STEM
AND GAGE (.015" GAGE INCLUDED IN
CARBURETOR KIT BT-3005)
BT-6428 OR J-25289
AREA WHERE GAGE SEATS MUST
BE CLEAN AND SMOOTH
Figure 10 Measuring Valve Stem Height (Bridge-type
Tool)
1. BT-6428 OR J-25289
IF VALVE STEM TIP IS LESS THAN .005"
ABOVE ROTATOR AFTER GRINDING STEM
INSTALL NEW VALVE
- - _ ^ ti?5754-j
Figure 11 Measuring Valve Rotator Height
V A L V E S T E M HEIGHT (STEEL RULE)
1. Place the valve in its guide and hold it in the
closed position.
2. With a steel machinists rule, measure from the
machined spring seat to the valve tip.
3. The measurement should be as specified in the
specific engine section.
V A L V E SPRING INSTALLED HEIGHT
Measure
m Valve spring installed height (Figure 12).
Excessive valve spring installed height is caused
by the lowering of the valve seat by wear and
grinding, and valve face grinding during
reconditioning. To correct the valve spring
installed height, add shims under the valve
spring.
1. Place the valve in the guide.
2. Install valve spring retainer and keepers.
3. Pull up on the valve spring retainer to seat it.