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1977 PONTIAC SERVICE MANUAL
Insert telescope hole gage in valve guide bore center
diameter to obtain valve to valve guide clearance. If clearance
is not within limits, use next oversize valve and ream bore
to fit using suitable reamer of tool J-5830-02 (Fig. 6A2-23).
Fig. 6A2-23 Reaming Valve Guide Bore (Typical)
10. Check valve spring tension with suitable tester (Fig.
6A2-24).
Fig. 6A2-24 Checking Valve Spring Tension
11. Springs should be checked by comvressing to a
specified height, and measuring force required to maintain
that height. (See Specifications) Weak springs affect power
and economy and should be replaced if below specified
pressure.
VALVE GUIDE BORE
Recondition
Valves with oversize stems are available for inlet and
exhaust valves. Guides should be reamed and new oversize
valves installed whenever clearances exceed specifications.
VALVES AND SEATS
Recondition
1. Reface valves and seats as follows:
Valves should be ground on a special bench grinder
designed specifically for this purpose and built by a reputable
manufacturer. Valve seats should be ground with reputable
power grinding equipment having stones of the correct seat
angle and a suitable pilot which pilots in the valve stem guide.
To ensure positive sealing of the valve face to its seat, the
grinding stones should be carefully refaced before any
grinding is done.
Valve seat angles should be 46" and valve face angles 45"
for proper seating.
Assemble
1. Starting with No. 1 cylinder, place the exhaust valve
in the port and place the valve spring damper assembly and
cap in position. Then using suitable spring compressor,
compress the spring and install new oil seal and valve locks.
See that the seal is flat and not twisted in the valve stem
groove and that the seat locks properly in the valve stem
groove (Fig. 6A2-2 1).
2. Assemble the remaining valves, valve spring and
damper assembly, shields, spring caps, new oil seals and valve
locks in the cylinder head. Check seals by placing a vacuum
cup over valve stem and cap.
3. Install cylinder head as previously described.
CRANK PULLEY HUB AND/OR
OIL SEAL
Remove
1. Remove drive belts.
4. Remove center bolt and slide hub and pulleys from
shaft.
3. Carefully pry oil seal from front cover with a large
screwdriver. D o not distort the sheet metal timing chain
cover.
Replace
1. Install new seal with helical lip toward rear of engine.
Drive seal carefully into place using tool J-23042.
2. Coat front cover oil seal contact area of balancer with
engine oil.
3. Position hub on crankshaft and slide into position
until it bottoms against crankshaft gear.
4. Install center bolt and torque to 160 lb. ft.
5. Install belt drive pulleys.
6. Install belts and adjust tensions.
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