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301-350-400 V 8 ENGINE VI CODES Y-P-Z
6A5-11
C
Fig. 6A5-2 1 Upper Valve Train Parts
I
Fig. 6A5-22 Cleaning Valve Guide Bore -Typical
By using a micrometer and a suitable telescope hole gage,
check the diameter of the valve stem in three places; top,
center and bottom.
NOTE: Exhaust valves in 301 have tapered stems and
are ,001 larger at the top than at the head end.
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 5-5830 (Fig. 6A5-23).
10. Check valve spring tension with suitable tester (Fig.
6A5-24).
11. Springs should be checked by compressing to a
special 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 .003" oversize stems are available for inlet
and exhaust valves. Guides should be reamed and new
oversize valves installed
whenever clearances exceed
Fig. 6 A 5 - 2 3 Reaming Valve Guide Bore - Typical
I
Fig. 6A5-24 Checking Valve Spring Tension
specifications.
VALVES AND SEATS
Recondition
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.
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