Piston Ring End Gap - Depth?

[Green993]

When measuring piston ring end gap what is the proper depth to place each of the three rings? Car is 993.

Also, I assume the measurement should be taken at the cylinder end closest to the head, right?

Lastly, the ring end gap for the top ring is .2mm, upper limit .8mm. What are the values for the other 2? These values are not in the shop manual.

[HawgRyder]

If you look down the bore of the cylinder...you will see the wear pattern on the wall.
When measuring ring gap...make sure to push the ring down into the worn area..so that you get a true reading on the gap.
If you gap the ring on the top area...where the bore is untouched..and then put the ring on the piston for install...the gap will be too wide.
Bob

[Lapkritis]

Originally Posted by HawgRyder

If you look down the bore of the cylinder...you will see the wear pattern on the wall.
When measuring ring gap...make sure to push the ring down into the worn area..so that you get a true reading on the gap.
If you gap the ring on the top area...where the bore is untouched..and then put the ring on the piston for install...the gap will be too wide.
Bob

+1

It is more critical not to have a ring gap that is too tight.

I normally use a piston without rings to set the ring in the bore squarely in order to check the gap. You can check at a few places in the bore; gap should be set for the tightest space. If you have wildly different values then you may need an over-bore/hone.

[AlfonsoR]

As you know, the ring gap has to do with thermal expansion. I am not an expert or professional engine builder but my strategy would be to go for the narrow end of the specified range at the tightest spot on the cylinder. This way you know you will be good no matter what.

Does the 993 have gaskets at the base of the cylinder? If so, the stroke pattern on your cylinders may possibly be different (ever so slightly) and may need to consider that for ring gap.

Are you using Goetz rings?

[Green993]

Originally Posted by AlfonsoR

As you know, the ring gap has to do with thermal expansion. I am not an expert or professional engine builder but my strategy would be to go for the narrow end of the specified range at the tightest spot on the cylinder. This way you know you will be good no matter what.

Does the 993 have gaskets at the base of the cylinder? If so, the stroke pattern on your cylinders may possibly be different (ever so slightly) and may need to consider that for ring gap.

Are you using Goetz rings?

Yes, Goetz rings.