What are your cylinders made from? If they are gunmetal then don't use piston rings.If they are cast iron, then piston rings are ideal; teflon impregnated soft packing is good if the slot is a good fit. "O" rings are fine if the bore has a high finish, or else they will wear rapidly.

Maurice

Making cast iron rings is not difficult, can't be as I managed it. Tubal Cain described it in ME many moons ago, but it was badly misprinted. Also described in his 'model engineers handbook, but the description of how to make was better in ME, just the equations (which you don't need to understand) printed wrong I think. The trick is to make them of small section, mine are 0.045" square in 1.5" bores. Don't use rings out of chain saw engine, too high wall pressure.

I might be able to dig out the articles if the tidying gremlin hasn't struck, let me know if you're interested. Of course if you already made the pistons this will be less attractive.

Edited By duncan webster on 04/03/2020 00:04:32

What piston seal for Bronze piston and GM cylinder ? SPEEDY 5" gauge