[SEL] Piston Rings and old engines.

[curt at rustyiron.com]

George,
Eons ago I posted a couple of pages on making piston rings using the heat
treat method to make the rings take on a new set. I opted not to try this
method, but rather try the fully machined method. On the 2 pages posted
are some guidelines about sizing the gap, etc. Here is the link. I have
not checked to see if agrees with the old rings I was working to.
<http://www.oldengine.org/members/holland/images/PistonRings/Thumbnails.html>

The 2 piston diameters for this project were 5" and 4 3/4". The 5" rings
had a 5/8" gap when relaxed and the 4 3/4" rings had a 1/2" gap when
relaxed. I'd guess the gap goes down with smaller rings and up with larger
rings. By measuring a range of rings some good guidelines could be
developed. Then one can do a little Pi work and figure the blank ring ID
needed to match up with a given ring groove diameter on a piston. I'd say
you want .020 to .025 under the ring on each side, or .050 clearance total
between the ID of the ring and the root of the ring groove for 5" rings.

Maybe some folks have some smaller and larger pistons out of engines at
the moment and they can tell us what the ring gaps are vs. the size of
piston.
It would be very useful information to chart.

Curt


> Wow!  I'm always impressed by how you tackle challenges and document
> what you do.
>
> One question.  If you didn't have an old ring to measure, how would you
> determine the inside diameter for your new ring?
>
> George
>
> -----Original Message-----
> From: sel-bounces at lists.stationary-engine.com
> [mailto:sel-bounces at lists.stationary-engine.com] On Behalf Of
> curt at rustyiron.com
> Sent: Thursday, October 02, 2008 11:08 AM
> To: stationary-engine at oldengine.org; sel at lists.stationary-engine.com
> Subject: [SEL] Piston Rings and old engines.
>
> Guys, here is a page I put together on fun in the shop last night. The
> weather is finally cooling off and I played on the lathe until about
> 10:30
> last evening trying my hand at making piston rings for a couple of
> friends
> who need some for their hit and miss engines. Hope you enjoy.
> Curt Holland
> <http://www.oldengine.org/members/holland/images/MakingPistonRings/Thumb
> nails.html>
>
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