George Breckenridge (Utterpower) sold the original Redstones in the U.S. Here in Canada they were sold by John Ferguson out of Ontario. They were hopper cooled, but came with an adapter plate to convert them to either pumped water cooling or thermosyphon. Some of the Utterpower site is still functional, but unfortunately the Redstone content is no more.
Here are c couple of links with photos of an adapter plate to replace the hoppers on the Changfa type engines, the Redstone adapter was much the same.
https://www.utterpower.com/diesel.htmhttps://www.utterpower.com/changfa.htmA friend bought a Redstone at the same time I got my Listeroid, we shared shipping costs. His is set up with a plate to allow thermosiphon, seems to work OK.
There were not very many imported by Breckenridge and Ferguson, as production stopped. The last ones to come to North America we reportedly assembled by "volunteers", that may be true, as we stripped one down on arrival and it was full of casting sand, untorqued bolts, and some stripped threads in the castings. After a really good internal cleaning and reassembly it ran (and still runs) well. What a beast though, it is almost unbearably noisy.
If the photos provided by Willw are indeed Redstones, and they are back in production, they are pretty well designed engines and may be worth having if they fit your power requirements.
Jim Calder (justliveoffgrid.com) bought out John Ferguson some years ago, and may still have Redstone parts. He sells Laidong single cylinder horizontals, as well as Listeroids and spare parts.
Cheers
Hugh
