993 Piston Ring SIde Clearances
 

What are the side clearances I should be looking for the rings on a 993 motor?

I need to determine if the ring grooves in a used set of pistons I just bought are acceptable. I installed the rings on a piston and then attempted to determine the side clearance using feeler gauges. It appears to be very little. I don't have a feeler thin enough to insert in the gap; but, the ring fits nicely into the groove without any sign of binding. It occurred to me that perhaps I need to take the side clearance measurement with the rings removed from the piston since the sides of the groove may not be parallel to one another. Is that possible?

For instance, Wayne's book calls for .07 to .102mm side clearance for the top ring for a 3.0/3.3 Turbo. Can I use that same criteria for my 3.6 motor? And should I take the measurement with the ring removed from the piston and by inserting an edge of the ring into the groove and determining the side clearance?

You should be able to take the measurement with the ring on the piston. How thick is your thinnest feeler gauge? I do not know the clearance needed for a 993, but I am assuming it will be similar to the earlier models.

I have an unusual situation in that the ring side clearance appears to be too LITTLE. With new Goetz rings installed on my used 3.6 pistons, I attempted to measure the side clearance on the top ring first. My thinnest feeler gauge is 0.062mm, and does NOT fit between the ring and the ring land. I should note that the ring can be rotated within the ring groove easily without any signs of binding.

When I mic the thickness of the new rings versus the thickness of the used rings that came out of the engine, I find that the new rings are slightly thicker than the new Goetz rings, which is supported by my inability to measure the side clearance of the ring.

So, my issue is should I send back the Goetz rings or am I good to go with the slightly closer fit that these rings produce in my piston? I haven't measured any of the other pistons yet, assuming that any ring found to be unacceptable will disqualify the entire ring set.