how to identify the correct big end bearings fore a 1.8 petrol engine

Here is the procedure to check bearing selection on big ends

1. Record big-end journal code letters from
crankshaft rear web.
First letter is number 1 big-end bearing.

Record big-end bearing bore code numbers;
this will be 5, 6 or 7, located on the connecting
rod bearing cap.
2. Check crankshaft big-end journal diameters:
Big-end journal diameter = 47.986 to 48.007
mm
Maximum out of round = 0.010 mm
Big-end journal tolerance:
Grade A = 48.000 to 48.007 mm
Grade B = 47.993 to 48.000 mm
Grade C = 47.986 to 47.993 mm
Clearance in bearings = 0.021 to 0.049 mm
Big-end/connecting rod end-float = 0.10 to 0.25
mm
3. Select the appropriate big-end bearing shells
from the table.
4. Replace crankshaft if outside tolerance.
Big-end bearings size
Big-end bore
Grade A Grade B Grade C
Crankshaft big-end journals
Grade 5 BLUE - BLUE RED - BLUE RED - RED
Grade 6 BLUE - YELLOW BLUE - BLUE RED - BLUE
Grade 7 YELLOW - YELLOW BLUE - YELLOW BLUE - BLUE
Colour code on edge of bearing
Thickness progression:
YELLOW - Thin
BLUE - Intermediate
RED - Thick
If two bearing colours are to be used, thicker bearing
must be fitted to big-end bearing cap.