Fitting Valve Stems To Guides; Valves And Seats Recondition; Cleaning Valve Guide Bore; Reaming Valve Guide Bore - Pontiac Grand Prix Service Manual

SIX CYLINI )ER ENGINE 6-17
Fig. 6-27 Cylinder Head Bolt Tightening Sequence
If clearance is not within limits, use next oversize valve
and ream bore t o j t using suitable reamer.
FITTING VALVE STEMS TO GUIDES
Correct valve stem clearance for valve guides is .0016"
to .0033" for the intake valve and .0021" to .0038" for
the exhaust valve.
Valves with oversize stems are available in .001", .003"
and .005" larger than standard. The same valve stem
to guide clearance applies for oversize stems.
Oversize reamers are required to enlarge valve guide
holes to fit the oversize stems. When reamer is turned
through valve guide, it will size the hole to fit valve
stem according to above limits.
Carefully ream the valve guide using valve guide
reamer J 5830-1 for .003" oversize stems and valve
guide reamer J 6621 for .005" oversize stems (Fig.
6-29). For best results when installing .005" oversize
valve stem use the .003 oversize reamer first and then
ream the .005" oversize. Always reface the valve seat
after reaming valve guide.
NOTE: Valves are marked
.001,
.003 or
.005
with
colored ink.
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 bebground
with reputable power grinding equipment haviog
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.
and intake valves have a seat angle of 46" with a face
angle of 45" (Fig. 6-30). This provides hairline contact
between valve and seat to provide positive sealing and
reduce build-up of deposits on seating surfaces.
DO NOT USE REFACING EQUIPMENT EXCES-
SIVELY;. only enougn material should be removed to
true up surfaces and remove pits. The valve head will
Fig. 6-28 Cleaning Valve Guide Bore
Fig. 6-29 Reaming Valve Guide Bore