Mercury MerCruiser Service Manual page 250

Engine Inspection and Assembly
NOTE: Several different types of equipment are available for reconditioning valves. The manufacturer's recommendation
should be carefully followed to attain proper results. Valves that do not meet specifications should be replaced.
a
Exhaust
a - Margin
b - Face angle
Description
Face angle
Margin after surfacing
Valve Seat
IMPORTANT: Regardless of the type of equipment, it is essential that the valve guide bores be free from carbon or dirt to
achieve proper centering of the pilot in the valve guide, ensuring concentricity when reconditioning the valve seats.
NOTE: Several different types of equipment are available for reconditioning valve seats. Equipment manufacturer's
recommendations should be followed to attain proper results.
1. Recondition the valve seats if pitted or worn.
a
Typical 3 angle valve seat
a - Top correction cut angle
b - Seat angle
c - Bottom correction cut angle
d - Seat width
Page 3B-48
b
b
Intake
Exhaust
Intake
b
c
© 2016 Mercury Marine
a
33021
Intake
6.2 Liter (377 cid)
0.79 mm (0.0311 in.) minimum
90-8M0099748 eng DECEMBER 2015
45°
45°
d
30201