TM 5-3825-226-24
CYLINDER HEAD AND VALVE COMPONENTS
The following procedure may be used to knurl valve
guide bores using the United Tool Process:
1. Clean and buff head, guides, and valves. Check
valve stem diameter. The intake valve stem
diameter is .3725 ±.0005 in. (9.462 0.013 mm) and
the minimum size worn is .3710 in. (9.423 mm).
The tapered stem exhaust valve has a stem diameter
of .3715 ± .0005 in. (9.436 ±0.013 mm) at the
keeper end of the stem, and .3705 ±.0005 in. (9.411
± 0.013 mm) at the head end of the stem. The
minimum size worn is .3690 in. (9.373 mm).
2. Place head on the FT806 Cylinder Head Bench or
8S6691 Cylinder Head Stand with spring end of
valve guides toward you.
NOTE
Use FT967 Adapter Plates to mount
head on FT806 Cylinder Head Bench.
3. Select the drill jig that corresponds in size to the
valve guide. Use the 3/16 in. drill and stop in a slow
speed drill. Drill an offset hole in guide 1/8 in. to
3/16 in. (3.2 to 4.8 mm) deep (hole to be drilled on
exhaust manifold side of guide).
4. Using the proper size knurling tool and wheel, insert
tool into guide and place wheel edge in offset notch.
Place one drop of lubricant in each offset notch
before knurling, and one drop on wheel after
installing wheel in knurling tool. Use straight hex
blade provided to match knurling tool and adapter in
speed reducer. Hold outer sheel of reducer from
turning and start drill. Follow the rotating tool with
slight pressure through the guide.
CAUTION Use the mechanical speed reducer for all
knurling and reaming as excessive speed and torque
destroys tools. If possible, use a drill with a no load
speed of 600 rpm.
5. After knurling all guides, and before reaming, try
valves in each end of guides. They should not fit into
guides. If valves will go in either end of guides, the
guides must be knurled again using the next size
wheel. Ream the guides with a .374 in. reamer
before knurling. Repeat knurling and reaming
process until valves will not fit into guides.
6. Ream valve guide bores to .3745 + .0005 in. (9.512
+ 0.013 mm). To ream valve guide bore use a .374
in. reamer. The reamer will ream the bore .0005 to
.0008 in. (0.013 to 0.020 mm) over the size marked
on the reamer.
7. After reaming, clean guides thoroughly before
checking valve guide bore size.
8. Before installing valves, clean valve guide bores with
the IP5571 Brush and a strong detergent. Stroke
each bore several times with the brush rotating to
remove all dirt and loose chips. After the valve
guides are knurled, the valves and valve seats must
be ground to provide proper sealing. For valve
grinding specifications, see VALVE GRINDING
SPECIFICATIONS CHART.
GRINDING VALVE SEATS
VALVE GRINDING SPECIFICATIONS
Item
Exhaust
Intake
Seat Angle
45 ½° + ½ °
30 ½° + ½ °
Seat Width
.105 in.
.120 in.
(Maximum)
(2.67 mm)
(3.05 mm)
Seat Outside
1.735 ± .005 in.
2.045 ± .005 in.
Diameter (new)
(44.07 ± 0.13 mm)
(52.23 ±0.13 mm)
Seat Outside
1.760 in.
2.065 in.
Diameter (Maximum)
(44.70 mm)
(52.45 mm)
Angle to Grind
Heads with
Insert to Reduce Seat
15°
inserts installed
Maximum Diameter
15°
Depth of Bore to
-
Heads without
Reduce Seat
inserts .170 in.
Maximum Diameter
(4.32 mm)
Valve Face angle
45° ± 1/4°
30° ± 114°
Valve Lip
.063 in.
.091 in.
Thickness (new)
(1.60 mm)
(2.31 mm)
Valve Lip
.044 in.
.070 in.
Thickness (Minimum)
(1.12 mm)
(1.78 mm)
1.804 + .005 in.
2.094 ± .005 in.
Valve Head Diameter
(45.82±0.13mm)
(53.19+0.13mm)
Maximum Distance
Valve Head to Cylinder
.085 in.
.068 in.
Head Face (Closed
(2.16 mm)
(1.73 mm)
Valve)
Minimum Distance
Valve Head to Cylinder
.050 in.
.036 in.
Head Face (Closed
(1.27 mm)
(0.91 mm)
Valve)
3-379
