Early Roundhouse Piston Ring Sizes

[Paul H]

I have been giving my Dylan a quick once over to maKe sure that all the normal mechanical maladies of a 30 year old loco have been addressed. There is no appreciable wear to the metal bits, but the packing gland rings were very hard and starting to shred, and the piston rings had a nice flat on the outer surface.

This brings me to my question, namely, what is the correct size of o ring for the original small bore cylinders? Roundhouse does not market a service kit for that size of cylinders at this time.

Thanks much,
Paul

[GardenSteamer]

Hi Paul,

Some of the early Roundhouses use 1/2" bore cylinders. Can you remove one of the cylinder covers and measure just to check?

Jim

[Paul H]

The piston is a bit over .465" and the bore is just under .470".

Paul

[GardenSteamer]

That seems to be a really odd size - almost 15/32". Probably the best thing to do is to phone Roundhouse and ask if they have any records for the cylinder bore they used way back then.

I have found them very helpful and they may even have some O rings in stock. Let us know how you get on.

Jim