[SEL] Piston Ring Size

[Robert L. Holtzer]

On 12/9/2011 9:34 AM, curt at rustyiron.com wrote:
> Kerry,
> I don't know if this would be helpful, but I documented rings I made for a
> couple of engines back in '09. The gap was ,625. On the diameter that
> works to about 0.2". So the rings were about 0.2" larger than the bore in
> the relaxed condition.
>
> The measurements you describe sound about right. I question the material
> and the radial thickness. As I recall I used Grade 30 cast iron. That
> 30,000 psi material. Nice and soft.
>
> See
> <http://www.oldengine.org/members/holland/images/MakingPistonRings/Thumbnails.html>
>
> Curt Holland
> Bessemer City, NC
>
>> G'Day All
>> I just pulled the piston out of an engine that I have that never had
>> very good compression, bore not brilliant but its the rings I am
>> questioning as when I pulled the piston out two of the rings looked too
>> big and requires a lot of force to push them in by hand to anything like
>> the piston size. The piston is 5.5 inch in Dia and the normal dia of the
>> outside of rings is 5.75, is that two much, width is 3/8.
>> Thanks for suggestions
>>
>> Kerry
>> Lithgow NSW Oz
>> _______________________________________________
>> SEL mailing list
>> SEL at lists.stationary-engine.com
>> http://www.stationary-engine.com/mailman/listinfo/sel
>>
>
> _______________________________________________
> SEL mailing list
> SEL at lists.stationary-engine.com
> http://www.stationary-engine.com/mailman/listinfo/sel
>
There are several ring gap calculators on the Internet.  Google 'piston 
ring gap calculation' for a selection.

R. Holtzer