[SEL] Re: Pinned Rings - Problems or Not?

[Jeff Allen]

Hi Arnie,

I'll have to agree with you. My Sattley has pinned rings, and judging 
from the general condition of the engine, it has been well used over the 
years. The cylinder wall shows no signs of wear from the pinned rings 
and the gap being stationary. I do believe that rings would catch on 
ports on two cycle engines, yet the Maytags live on and on, so I really 
doubt that the rings rotate. Same goes for other two cycles I have 
worked on by the way.

 From my limited knowledge of engines, when wrist pins contact cylinders 
you have shrapnel. The wear marks in the cylinder tell you why. My too 
sense worth.

Jeff Allen

Arnie Fero wrote:

>Hi Bill,
>
>Allow me to offer up a technical term on this line of reasoning.
>Bullshit.
>
>The problem with the two examples offered; namely a wristpin that pokes
>out and wears a groove in the cylinder wall and a stuck piston ring
>producing abnormal cylinder wall wear, is that neither one represents what
>happens with normal pinned piston rings.
>
>A normal ring makes contact uniformly with the piston wall and the oil
>film based on the amount of "spring" that the ring has.  A stuck ring
>can't move away from the wall, neither can the wristpin.
>
>My 4 hp Robertsonville (a 4-stroke engine) has pinned rings.
>Take a look at...
>http://www.oldengine.org/members/arnie/Piston_Rings/rings_1.jpg
>http://www.oldengine.org/members/arnie/Piston_Rings/rings_2.jpg
>http://www.oldengine.org/members/arnie/Piston_Rings/worn_rings.jpg
>
>As you can clearly see the rings are BADLY worn (not stuck).  The cylinder
>wall had no indications whatsoever of any abnormality caused by the "ring
>ends" even though the rings are pinned.  BTW I kept the pins when I
>replaced the rings.
>
>My two cycle Bessemer half-breed also has pinned rings, a lot of ring and
>cylinder wear and no indication whatsoever of "ring end" effects.
>
>Engine builders dropped the idea of pinned rings in 4-stroke engines for
>one reason only.  The added cost was not offset by any performance
>improvement.  Not because it caused problems.  We obviously don't see
>problems in our two-stroke engines with pinned rings.
>
>See ya,  Arnie
>
>Arnie Fero
>Pittsburgh, PA
>fero_ah at city-net.com
>
>On Fri, 15 Apr 2005 bill at antique-engines.com wrote:
>
>  
>
>>You'll wear a ridge where the ring gap is.
>>http://www.sacskyranch.com/piston_ring_rotation.htm
>>
>>One way to show rotation is to disassemble an automotive engine - and look
>>at the spot where the top ring lands in the cylinder at each TDC - if
>>there was no rotation, you should see where the ring end gap left an
>>unworn area in the cylinder, but you won't unless the rings were stuck.
>>It's worn all the way around.
>>
>>    
>>
>>>bill at antique-engines.com wrote:
>>>
>>>      
>>>
>>>>On a 4 stroker it's normal and preferred.
>>>>
>>>>        
>>>>
>>>Please elaborate. Why is ring rotation preferred as opposed to being
>>>pinned in place?
>>>Curt
>>>      
>>>
>
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>  
>