Valve Springs - Checking Tension; Valve Seat Repair - Mercury MerCruiser MCM 454 Mag MPI Service Manual

454 CID (7.4L) / 502 CID (8.2L)

Valve Springs - Checking Tension

IMPORTANT: Springs should be replaced if not within 10 lb. (44 N) of specified
tension.

Valve Seat Repair

Valve seat reconditioning is very important, since seating of valves must be perfect for
engine to deliver maximum power and performance.
Another important factor is valve head cooling. Good contact between each valve and its
seat in head is important to ensure that heat in valve head will be properly dispersed.
Several different types of equipment are available for reseating valve seats. Equipment
manufacturer's recommendations should be followed carefully to attain proper results.
Typical "3 Angle" Valve Seat
Index
Page 3A-44
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a
a - Valve Spring Tester (J-8056)
b - Torque Wrench
a - Top Angle (30
)
b - Seat Angle (46
)
c - Bottom Angle (60
)
d - Seat Width
Intake - .060-.090 in. (1.52-2.29 mm)
Exhaust - .060-.090 in. (1.52-2.29 mm)
b
a
b
d
c
SERVICE MANUAL NUMBER 23
72308
50668
90-861326--1 MARCH 1999