ENGINE 1.3 QUADRAJET (75PS)
55
Above is an example of identifying the main journal
and crankpin grade referring to an engine with nominal
diameter main journals (51.000 mm).
1) Crankpin alphabetical identification code - BBBB
(the same for all bearings): the first letter from the
left refers to the first timing side bearing.
2) Main journal alphabetical identification code -
AAAAA (the same for all bearings): the first letter
from the left refers to the first timing side bearing.
3) Alphabetical identification code for thrust washers
- R.
Only use the alphabetical codes for references 1, 2
and 3 in the diagram, all the other codes on the
counter-weight should not be used.
For the identification of the main journal grade, refer
to the alphabetical code 2 shown in the diagram.
In the case of the diagram, for example, the letter
code AAAAA (Grade A - Normal) indicates that all
five bearings are prepared for the fitting of half-
bearings with a Red coloured paint mark on the edge;
as a result, specific half-bearings should be identified
for different alphabetical codes (bearing grade).
The letter code stamped on the timing side counter-
weight is required for selecting the grade.
Normal grades are usually used on new engines with
undersizes only used in exceptional cases.
ALLOCATION OF HALF-BEARINGS TO MAIN
JOURNALS:
Having defined the grade for each crankshaft bearing
(to which a specific diameter corresponds according
to the grade), it is necessary to select the p air of
Main journal grade
Diameter
Paint Mark
grade A (normal) 51.000 ~ 50.994 mm RED paint mark
grade B (normal), 50.994 ~ 50.988 mm BLUE paint mark
grade C (normal), 50.988 ~ 50.982 mm YELLOWpaint mark
grade AM
(0.127 undersize) 50.873 ~ 50.867mm BROWN paint mark
grade BM
(0.127 undersize) 50.867 ~ 50.861mm, GREEN paint mark
grade CM
(0.127 undersize) 50.861 ~ 50.855mm BLACK paint mark
Minimum
Maximum
0.025 mm
0.052 mm
bearings which are the same colour. This is designed
to guarantee the optimum operational clearances for
all the bearings.
Lastly, we wish to point out that, generally , the
clearance between the main journal and the half-
bearing, obtained through the selection method
indicated above, should be within the following values:
