[coriducu]

Finding the accurate oil clearances for each and every engine is very tedious job. Improper oil clearances can lead to serious damage to the engine. I have been in the field of automotive repairing and maintenance since 1976. I have always relied on my formula which is as under. It may be helpful to other members as well. Just try it, if it is found useful, make it your own otherwise discard it. It may vary +/- 0.005 mm from the OEM data. The answer is almost compatible with the OEM values. You may try this confidently whether the engine is gasoline, diesel, car or truck. I have not received a single complaint so far.
Diesel Engine:
NOTE: Always measure the piston to cylinder clearance with the help of cylinder gauge and micrometer.
To find the piston to cylinder clearance of diesel engine at room temperature:
Piston to cylinder clearance = 0.0008 X Piston diameter in mm. (Diesel car, Diesel truck or Diesel Generator). (NOTE: Always measure the piston diameter at the distance of 12.5 mm from the lower edge of the piston skirt, perpendicular to the piston pin at room temperature).
The piston ring end gap will automatically come to its default clearance. To verify, insert the top piston ring into the cylinder with the mark pointing upward, push it about 20 mm down with the piston from the cylinder top face and measure the oil clearance with feeler gauge.
multiply 0.0045 X piston diameter = Ring end gap.

To find the piston to cylinder clearance of gasoline engine at room temperature:
Piston to cylinder clearance = 0.0007 X piston diameter mm.
Hope that works.
Thanks.

m8 thanks for your help but this what you say can be found on each,piston/cylinder manufacturer catalog,I'm interested especially in cylinder head data