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Clupet Rings and Piston Rings

Made to order, any size!

Rufford Steam Works offers custom made rings of both plain and clupet type, for fitting to pistons and piston valves. Most rings are made from 250 grade cast iron, although we have made rings in SAE 660 bronze for sealing against stainless shafts. We have made a wide variety of clupet rings, from 3/4" for 5" Gauge Piston Valves to 9" for a full size Double Fairlie, and 12" for ploughing engines.

Plain rings can be made butt joints or 45° scarf joints. Plain rings provide good sealing characteristics on new, or unworn bores. If the bores become worn, they will wear more in the middle of their stroke, meaning the ring has to grow and contract on every stroke. With a plain ring, this creates an easy gap for gasses to pass, as rings have to be sized to the smallest diameter of the bore. Due to the design of clupets, this does not happen, which is why we always recommend clupets if there is ever a doubt in the condition of the bores, and can extend the time before a rebore is needed. This is also the reason why clupets can have a much longer service life than plain rings. 


Remember.. Circumference = π x Diameter.. So a 0.001" difference in bore diameter is over a 0.003" change in ring gap!!


We can make rings to suit your current pistons and bores exactly. Even if your bores are only 0.001" different to each other, we can provide rings to suit each bore. As such, it is important to get a nice accurate bore measurement where possible, to ensure trouble free fitting and the best possible seal. If your unsure of what rings dimensions are best, or what tolerance pistons grooves should be, we'd be more than happy to advise.

We keep a small stock of rings from overruns, ready for their final o.d turn, although most rings are made to order. Usually rings are ready to dispatch within 3 weeks from placing an order. We regularly undertake the machining of pistons, be they solid or split with suitable rings as a package. 


Please email us at with your requirements and questions or ring Tim on 07516852988 for a quote.

Testing a 7 1/4" Greenly Royal Scot after cylinder work

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