[Freemasm]

Trying not to clutter someone else’s thread.

Maybe I was taught wrong a long time ago. I always thought that piston rings were supposed to rotate, continually over time during operation. This is stated in a lot of text books but none were specific to GA PPs. If they didn’t, it could lead to problems. Made sense to me.

In another thread, somone’s jug had a badly fouled lower plug and oil visible via bore scope. No direct evidence of stuck rings and i believe a flush was performed. The culprit was determined to be ring gap alignment.

So the usual arguments; oil ring versus compression ring duties, related effects manifesting in compression tests versus oil consumption, etc being acknowledged. Will a jug removal with ring reclocking have a real long term effect? Of course the “repair” action could remedy a different culprit as a consequence.

Get me smarter. Anybody?

 

[rv8ch]

I understand it the same as you. I recall in my two-stroke motocross days we had pins in the ring groove to keep the rings from rotating since they would hang up on the ports. Four-stroke piston rings should rotate.

 

[Snowflake]

There's nothing to prevent rotation, nor anything to promote rotation, as far as I know. They just float there, and over time may or may not rotate as they see fit.