Kubota EA330-E4 Series Workshop Manual page 111

EA330-E4, WSM
Correcting Procedure for Valve Seat
NOTE
• Always try to minimize the valve seat recession.
1. Correct the valve seat surface with a 0.79 rad (45 °) valve seat
cutter.
2. Place the valve and visually check the contact position between
the valve face and valve seat with red lead.
(If the valve has been used for a long period of time, the seat
tends to come into contact with the upper side of the valve
face.).
3. Cut the seat with a 0.26 rad (15 °) valve seat cutter so that the
valve seat width makes contact in the same dimensions to the
valve face width.
4. Cut the seat with a 0.79 rad (45 °) valve seat cutter again, and
visually recheck the contact between the valve and seat.
5. Repeat steps "B" and "C" until the correct contact is achieved.
6. Continue lapping until the seated rate is more than 70% of the
total contact area.
(1) Valve Seat Cutter
(2) Identical Dimensions
(3) Seat Surface Width
(a) 0.26 rad (15 °)
(b) 0.79 rad (45 °)
(c) 0.79 rad (45 °)
(d) 0.26 rad (15 °)
(e) 0.79 rad (45 °)
Correcting Valve Seating (Valve Lapping)
1. Apply compound evenly to the valve lapping surface.
2. Insert the valve into the valve guide. Lap the valve onto its seat
with a valve flapper.
3. After lapping the valve, wash the compound away and apply oil,
then repeat valve lapping with oil.
4. Apply prussian blue to the contact surface to check the seated
rate. If it is less than 70 %, repeat valve lapping again.
IMPORTANT
• When valve lapping is performed, be sure to check the
valve recessing and adjust the valve clearance after
assembling the valve.
Oil Clearance between Valve Stem and Valve Guide
1. Remove carbon from the valve guide bore.
2. Measure the valve stem O.D. with an outside micrometer.
3. Measure I.D. of the cylinder head valve guide at the most worn
part with a small hole gauge, and find the oil clearance.
(Normally, a greater wear results in parallel to the rocker arm.).
4. If the clearance exceeds the allowable limit, replace the valve
guide and valve.
Factory specification
Oil clearance between
valve stem and valve
guide
Allowable limit
Valve stem O.D. Factory specification
Valve guide bore I.D. Factory specification
1-S46
ENGINE
A: 0.79 rad (45 °) Cutter
B: Contact Check
C: 0.26 rad (15 °) Cutter
D: 0.79 rad (45 °) Cutter
E: Contact Check
9Y1211018ENS0075US0
9Y1211018ENS0076US0
0.035 to 0.065 mm
0.0014 to 0.0025 in.
0.1 mm
0.004 in.
6.960 to 6.975 mm
0.2741 to 0.2746 in.
7.010 to 7.025 mm
0.2760 to 0.2765 in.
9Y1211018ENS0077US0
KiSC issued 05, 2015 A