Perkins 900 Series Workshop Manual page 80

4
To check the height grade of a piston
Piston height grades B, C and D have been used in production engines. This is now reduced to two grades, X
and Y.
Identification of the height grade of each piston is by a letter that is stamped on the top of the piston (A). There
are two grade letters, X and Y. Letter X is the higher grade and letter Y is the lower grade.
If a new piston is fitted, ensure that it is of the correct height grade. The height grade can be checked by
measurement, from the centre of the gudgeon pin to the top of the piston (B1).
l The dimension for grade X is 62,10/62,15 mm (2.445/2.447. in).
l The dimension for grade Y is 62,02/62,07 mm (2.442/2.444 in).
The table below shows the equivalent height grade needed when a new piston is to be fitted.
Old Grade New Grade
B and C
D
When a new piston assembly has been fitted, check that the height of the piston above the top face of the
cylinder block is 0,23/0,35 mm (0.009/0.014 in), see Operation 4-6.
X
A
70
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X
Y
X Y
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B
Workshop Manual, TPD 1345E, issue 3
900 Series
Operation 4-7
1
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