It feels like Spring here in Berkshire (well it does out of the wind anyway). The sun is shining, snowdrops are coming through my newly-laid turf and the nights are getting a little bit lighter. Time to crack on with all the projects which have been languishing over Winter.
An on-going little job over the last couple of weeks has been trying to get friend Bob's Tangye steam engine running properly. It's a nice horizontal engine, about 4x6 bore and stroke, probably built around 1900. It's been lobbed in his back yard for some years but he's recently got it up together and built a stand for it. However, connected up to the big Cornish boiler in his back yard, it did nothing but whoosh steam out of the exhaust pipe - it would just about run with 60 pounds on the clock.
First thought was the slide valve. We looked at it but it seemed ok - a bit pitted but nothing very much. Next thought was the rather narrow bore plumbing which connected the boiler to the steam chest. We hatched a theory that there was insufficient volume of steam getting into the valve chest to bang the valve down onto the port face. I brought the valve and rod down home and rigged up a spring, pocketed into the valve which pushed aginst the valve rod - this worked beautifully on the bench, keeping the valve in contact with the port face even upside down. With great hopes we tried again, with absolutely no improvement! Pulled it all apart again, took a quick skim off the valve and put the block up on my biggest angle plate and took a cut across the port face, which showed several hollows. In the end I took just over 30 thou off to clean it up - the Tangye now runs very sweetly on 15 psi.