[SEL] Stuck Piston Rings

[Rob Skinner]

On Apr 29, 2009, at 1:04 PM, Jerry Evans wrote:
>  No disrespect meant, but why is it so important to save the old  
> rings?


Hi, Jerry.  I've not restored nearly enough engines to gather adequate  
data to provide scientific facts, but I have some strong thoughts on  
the subject.  As an engine is run, the rings wear, the ring lands  
wear, the piston wears and the cylinder wears.  All these bits wear to  
match one another.  The taper of the ring grooves will match the  
rings, and the rings will match the out-of-round cylinder.  These  
mated surfaces can make a reasonable seal.

If you go and put round rings in an oval bore, or square rings in a  
tapered groove, you won't have a good seal at all.  New rings can be  
WORSE than old rings.

Last year I did a brief article on fitting new rings to an old  
piston.  The cylinder bore was very good, but the rings were broken  
when I got the engine.  http://engines.rustyiron.com/articles/ 
piston.pdf  The file is PDF and about 6 megs, so it might take a few  
minutes to send the file down your way.


	
Rob Skinner
Antique Stationary Engines
La Habra, California

rob at rustyiron.com
www.rustyiron.com