Roush wants my Alum. FE 511 motor

[Woodz428]

Originally Posted by Barnsnake

Two-stroke outboards have ports in the cylinder walls so the rings MUST be pinned to keep the ends from clipping in the ports. In addition to the added complexity and expense, the pins can cause problems themselves. They can work outward and score the cylinder. They can also get loose and migrate through the piston crown.

I worked 30 years in the bike industry, it is my opinion that they put the pins in to insure proper location so they don't hook in the ports. I accept that they move some, but I don't think they "rotate" which would indicate circling in the ring groove. Because there are precise locations the end gaps are set at, if the rings rotated they surely wouldn't rotate exactly the same and at some point all the gaps would line up for a period. Usually when ring sticks, it is the sealing against the cylinder that is the problem, not that it can't rotate. The same 2-strokes that are pinned don't rotate at all and seal,they also "stick" rings causing a loss of sealing. It still seems unlikely there would be more than a minor "oscillation" in the ring movement back and forth because of the crosshatch. Again, pistons are soft compared to ring material, and a constant rotation would effectively wear the ring groove out in no time,especially moving up and down so rapidly. As I pointed out earlier, the ring land that takes the worse beating is the top one from being so close to the heat. Except in a case of piston seizure, I don't recall ever seeing a second groove wear out. Rings are also of various configurations, some dykes type, some with a taper on one edge....with no particular concern for rotation, but for better cylinder wall sealing. In the 30 years in the bike business I pulled down at least 100 sportbike engines as well as snowmobile and dirtbikes,watercraft and offroad vehicles. I always examine every part on disassembly and have never seen a set of rings that had gaps staggered differently than how they were installed. There may have been some minor variances,but since they are installed by eye instead of some precise gauge, the variance could just be from the assembly. Once again that would indicate that all the rings rotate equally, which seems unlikely as well since they are constructed 3 different ways, of 3 different materials. Maybe there's one of those engineering clips with a clear cylinder that would show some, but I haven't seen one.

[DAVID GAGNARD]

I don't think the rings actually rotate per se, but they do move from the installed location......After about one hour of break-in and dyno time on my pressant race motor, I changed the oil and filter and when I drained the oil, I found about a quart of water in the pan, so I tore the engine down to see what the problem was.....(failed head gasket)

As I tore it down, I was very careful with everything as this was a brand new BOSS 302 block and I just knew it had a crack in it somewhere and would have to send it back to Ford. I took photos to document any and everything I did and found and what I found was a failed head gasket, causing the water in the oil..
I also found that the rings on 4 pistons had "move/rotated" some from the original position..... I made sure checking 2 or 3 times each piston as to the location of the ring gaps before installing them in the block, the rings were put as per directions on the box (Mahle rings).....on 3 pistons the ring movement was not very much, may 20 to 30 degress at most, on the forth one, the top ring had rotated enough so that the gap was lined up with the gap of the second ring, not good..... I checked with a number of engine builders and they told me they had seen this before, kinda normal for some rings to rotate some, they all said depending on the ring type/manufacter, some rings "move" more than others.........

on other engines I've done, ring movement/rotation has been minor....

Had I not seen it myself, I would have never thought the rings would rotate....

David