Hello, does the piston ring move around as the engine is running, it seems i could see the end gap,,,, a while later i had the engine off and could not see the gap through the exhaust opening, any help would be great.... thanks....

Yes, some rings move like that in normal operation.

Wow, i thought maybe i was seeing things !!! thank you for the reply, learn every day,,,

FlyBy, Barry,


Most Schnürle ported engines have a pinned ring that cannot rotate. The gap would be oriented in one direction only, always.

Some baffle-piston engines have their ports multi-bridged; essentially splitting a large bypass into several small ones... that cannot catch a ring-end.
Such was the HB.40PDP, which had a free-to-rotate Dykes ring.

Thats what i remember, i only replaced one ring in my life, it had a pin, i think it was a super tigre .61.... which would keep the ring in place,,,, my mind is slipping.... thank you.....

Well at least your mind slipped in the right direction....your doing a fun hobby...RC!

Thanks Brother, i thought maybe i was'nt buying enough engines,,,,,

You NEVER have enough engines.

Actually all baffled-piston ringed engines have multiple ports and unpinned rings which definitely rotate as the engine is running. I remember idly flicking one over and watching the ring gap very slowly moving around. The usual set up on these engines is 4 ports on the transfer side and 5 on the exhaust which is wider than the transfer side. Schneurle engines need a pinned ring because their transfer ports are quite wide although not so wide that the ring can expand into it. The much wider exhaust port though usually has a bridge in the centre for ring containment.

Quote:

ORIGINAL: downunder

Quote:

ORIGINAL: DarZeelon
Some baffle-piston engines have their ports multi-bridged...

Actually. all baffled-piston ringed engines have multiple ports and unpinned rings which definitely rotate as the engine is running.

Most maybe, but not all, Brian.

See this photo of this baffle-piston McCoys, stated to be ringed (I specified 'ringed' as part of the search).

Nah, they're the old lapped piston McCoy Dar. I used to have one of the ringed disc valved McCoy 29s though. From memory (I'm on holidays right now) I've got 9 baffled piston ringed engines.

Perhaps you are right, Brian.

With the size of the ports in these engines, something obviously must be done to keep the ring at bay.


Enjoy your vacation!

Dar, if those are .36s, I still have one I got for Christmas in 1955 at age 13. I also have a .35 I bought about a year later for $3.95. No rigs though.

PS, I know you're interested in Lynda's recovery, she had a huge setback on Jan. 30, when she was in a bad car wreck and broke her back in two places. She's once again in our care and takes up most of our time. She has to wear a two piece form fitting back brace before she can stand and walk. She should be free of the brace in two months.

I always thought that once a ring gets seated or bedded in, it stops rotating. The micro grooves and imperfections prevent it from rotating as it takes on the shape of the cylinder itself.