02-10-2017, 09:05 AM
Once upon a time, there were tests made with a special ring made of the flat .024 stock Mac used. The ring made one revolution, had a zee bend upward over the other end of the ring and continued around back to the zee bend. It was essentially a full circle .048 thick ring very similar to a Smalley Spiralox retaining ring. There was enough distance between the ring ends and the zee jog to accommodate expansion. The test Mc6 engine ran like wildfire, but the ring was just too expensive to make commercially. I can't remember who did this experiment. I just remember my Pop trying like the Devil to get hold of some. It was a normal thing for us to have Wiseco machine pistons with a single.053 groove, and we ran two .024 unpinned rings in a single groove. Of course, unpinned rings wouldn't be safe in an engine with a big single exhaust port, but these were earlier engines. We didn't square the exhaust ports, but rather gave the top of each port an arc to help guide the ring ends. The truth is that we should've pinned the rings from the piston wall rather than the crown. This would've meant that the gap, though aligned, would've occurred at a solid part of the cylinder liner. TJ