3.6L Piston and Cylinder dimensions

[rothaus]

I just want to confirm that the set of P and C. I have are OK to use.

Cylinders based on the manual Group 5 - 0 should be 100.000 + 0.007
I checked the cylinder roundness check and they all measure around 100.01 - 100.03. The largest roundness difference is 0.015.

Pistons based on the manual Group 0 should be 99.970 - 99.980
They all measured between 99.978 - 99.984

The clearance piston Cylinder is between 0.032 - 0.038

For the 3.2L piston/Cyl in the manual it is specified the the cylinder should be replaced if the roundness difference between A and B is more than 0.04mm

Also Cylinder should be replaced if measured diameter exceeds 0.08mm from installed size.

Also piston and Cylinders should be replaced if running clearance exceeds 0.12mm.

There nothing in the specs in my 964 manual.

However, if I apply the same limit to the 3.6L piston and cylinders, they should be good to go.

Do I miss something ?

Any input would be appreciated.

Thanks
Engelbert

[Henry Schmidt]

Your pistons and cylinders should be fine [based on your measurements].
Ovality [I know, not really a word] is difficult to measure accurately. This measurement should actually done in a torque plate. Until the cylinder is compressed [the condition seen in the engine] you really don't know it's installed specification/measurement.

Be sure to verify ring groove clearance.

Ring grooves in pistons also play a major role in sealing combustion pressure and controlling oil and blow-by.
While various types of piston rings are more suitable to specific applications, the ring grooves themselves are often overlooked in the pursuit of optimum cylinder sealing.
Many engine builders go to great lengths to file precision end gaps, but ring clearance in the groove frequently goes unchecked and the quality of the ring groove sealing surface is rarely considered. Clearance and ring groove quality are frequently assumed.

While used parts offer great cost savings they also present a plethora of challenges.

[rothaus]

Henry, Thank you for the reply.

Now I can go and clean all parts and take on the other important measurement as you pointed out.

Thanks
Engelbert