Lotus TURBO ESPRIT Service Manual page 197

SECTION EA
Page 50
A
Remove the main bearing shells, refit the
main bearing panel, and measure the
main bearing bore diameter.
S tandard bore d i m e ter
+0.015" O/D
bore diameter
2.6655
-
2.6660 in.
(67.704
-
67.716m)
2.6505
-
2.6810 in.
(68.085
-
68.097mrn)
As a cross check, look for the number stamped on the outside of any main bearing
shell with a
GROOVE
and HOLE
'5690'
=
Standard Outside Diameter
'5946'
=
+0.015" Outside Diameter
Block assemblies bored +0.015" oversize on production are normally identified
as follows:
-
907 Engines
'+015' stamped externally on flank at rear of main bearing housing, together
with red paint.
912 and 910 Wet Sump Engines
'15' stamped on 4th or 5th main bearing 'cap' (along with another 4 or 5 digit
number). Block may also be 'stamped in the region of engine number (above
starter motor)
.
910 Drv sum^ Eneine
Stamped externally on side of M.B.P. above rear
of
scavenge manifold.
Undersize inside diameter shells to suit reground crankshafts are available
for both standard and +0.015" overbored blocks. See Parts List.
MODIFICATION OF 910/912
WIN BEARING PANEL, PRIOR TO ENG. NO 20875
A l l 91 2 (natuml.ly aspirated 2.2
I
itre) and
91 0
(turboc
barged
2.2
l
itre) engines from engine number 20875, incorporate a
revised main bearing panel casting ta enable the rear face of
No. 5 main bearing to be fully machined i n order to reduce
o i l drain off from the thrust washer face.
This
pane1 does not
have the chamfer on No .5 main bearing as detailed below.
A l l engines prior to 20875 should have the following modification
carried out ONLY i f stripped for any other reason, and show
evidence of crankshaft thrust collar wear.
i )
Engines with numbers 20793 to 20874 inclusive have been
modified i n accordance with these instructions at the factory,
a
together with approximately thirty engines prior to 20793.
These engines require no further action but care should be
AP R 1987
taken to order the axrect m i n bearing s he1 Is (see paragraph
3).