Valves And Valve Seats; Hand Grinding - Perkins 4.108 Workshop Manual

E15
Inlet
INLET
VALVE
A-1.530 in to 1.531 in
8-0.3125 in to 0.3175 in
EXHAUST
VALVE
C-0.015 in chamfer at 45 (Max.)
Exhaust
A-1.296 in to 1.297. in
8-0.3125 in to 0.3175 in
C-0.015 in chamfer at 45 (Max.)
VALVES AND VALVE SEATS
The valves should be checked in their respective
guides for wear and replaced if wear has taken place.
(ensure that the wear is in fact on the valve stem and
not in the guide bore before replacing the valve).
The valve and valve seat faces should be reconditioned
in the normal way using specialised equipment or with
grinding compound, according to their condition. A
valve seat (hand operated) cutting tool is shown in
Fig. E.12. Valves should always be refitted to their
original seats and any new valve fitted should be suit-
ably marked to identify its position if removed at a later
date. (Refer to Fig. E.6 for illustration of valve num-
bering) .
Before refitting the valves it should be ascertained
whether the valve head depth relative to the cylinder
head face is within the limits given on Page B.2. This
depth can be checked, as shown in Fig. E.13, by
placing a straight edge across the face of the cylinder
head, then by careful selection of feeler guages mea-
suring the distance between the straight edge and the
head of the valve.
Where vehicle engines have to conform with the smoke
density regulation B.S.AU 141a: 1971, then valve depths
must not exceed production limits as given on page
B.B.
Where this depth exceeds the maximum limit and even
the fitting of a new valve does not reduce this depth
below the maximum limit, then the remedy is to fit a
valve seat insert as detailed later.
When refacing valves or valve seats care should be
taken to see that only the minimum amount of metal
necessary to obtain a satisfactory seat is removed, and
that as narrow a valve seat as possible is maintained.
Hand Grinding
When grinding or lapping·in valves make certain that
all signs of pitting are removed from the seats.
CYLINDER HEAD-E.S
k
c
tot
_I
!
I
; 1
-i........
GRAD
A
B
t
.
F
\. 0
. 1
E16
Material EN32A Case Hardened and Ground
Inlet Dimensions
A-2.75 in
8-2 in
C-0.75 in
0-0.309 in to 0.310 in
E-1/16 in at 45
F-1/16 in at 45°
G-1/32 in Radius
H-1.238 in to 1.239 in
J-0.222 in to 0.225 in
K-1.523 in to 1.533 in
Exhaust Dimensions
A-2.75 in
8-2 in
C-0.75 in
0-0.309 in to 0.310 in
E-1 /1 6 in at 45
°
F-1/16 in at 45°
G-1/32 in Radius
H-1.018 in to 1.019 in
J-0.222 in to 0.225 in
K-1.287 in to 1.297 in
After all the valves have been lapped in the valve head
depths relative to the cylinder head face should be
checked to ensure that they are within the limits given
on Page B.B.