Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Very Cool.

Do tell more…

Built with four screw cylinders!

But it is such a late model otherwise, I have to wonder if that was done by Jensen or ...... ?

Whatever the story may be, that is one very cool difference, and should make for one very powerful steam plant!!!

Quote from: Stoker on June 07, 2024, 05:32:21 pm

Built with four screw cylinders!

But it is such a late model otherwise, I have to wonder if that was done by Jensen or ...... ?

Whatever the story may be, that is one very cool difference, and should make for one very powerful steam plant!!!

Yes! Good eye!
I was told by the seller that his father bought the engine new. So I am assuming it came from Jensen Mfg that way.
The thing is, you can’t just steal two four screw cylinders from a couple 25 models and put them on a 55. One of the cylinders has to be a mirror image of the other one.

True that!

But well within the capability of many machinists to invert a steam chest on one of these.

Still, there seems no limit to the wonderfully nonconforming material that has leaked out of Jeanette PA over the years!

I'd have to think that if it is a one-off (or extremely limited) Jensen product, there would likely be some form of notation on the bottom of the baseboard?!?!

Custom Order? Prototype?? Perhaps of Extra-Terrestrial Origin???

Very cool and very interesting. Congrats, Mike..!!!

I built a 55 with 4 screw cylinders and I believe they are bigger than what are on your newer engine.

I also think this one has smaller screws than what Jensen uses on their 4 screw cylinders.

When you receive it, please measure the outside diameter and compare to your pre-war #25 cylinders and let us know.

Whatever the origin, the modification work looks excellent!

Thanks, Gil!
I can’t wait to examine it when it arrives on Monday. 😁
One thing I find interesting is the early style block-off plates used on the valve chests. If someone modified the normal cylinders that would be found on an engine like this, I would think the valve chests would have the rivets plugging the holes like you’d usually find.

Quote from: Junkologist on June 08, 2024, 06:43:39 am

Quote from: RedRyder on June 07, 2024, 10:21:26 pm

Very cool and very interesting. Congrats, Mike..!!!

I built a 55 with 4 screw cylinders and I believe they are bigger than what are on your newer engine.

I also think this one has smaller screws than what Jensen uses on their 4 screw cylinders.

When you receive it, please measure the outside diameter and compare to your pre-war #25 cylinders and let us know.

Whatever the origin, the modification work looks excellent!

Thanks, Gil!
I can’t wait to examine it when it arrives on Monday. 😁
One thing I find interesting is the early style block-off plates used on the valve chests. If someone modified the normal cylinders that would be found on an engine like this, I would think the valve chests would have the rivets plugging the holes like you’d usually find.

.
The extra large exhaust pipes and the early style port covers (on the steam chests) are features found on mine due to the early cylinders I used. I have only seen the large exhaust ports on the smaller military air pumps Tom Sr. made for the DOD.

Gil,
These cylinders measure 1” OD just like all my pre-war cylinders. The engine base casting does have the corners ground off where the cylinders mount. There is also a washer behind each crank to accommodate the wider spacing of the cylinder centers due to their size. The plywood base is actually beveled like most are and it’s larger than a normal 55 base. The original box is marked for a model 20 engine.  I believe this engine was built this way by Tom Jensen Sr as an experiment or just to use old cylinders that were laying around. He may have made a bunch of these cylinders that the DOD never needed and just wanted to use them up. Your guess is as good as mine, but I really can’t see some hobbyist just having these cylinders and doing this modification in their home shop on their own.

Mike:

Congratulations on a rare find!

When do you think this engine was built?

Hopefully, you will steam it and post a video for all to drool over.

Charlie

Thanks, Charlie!
I believe this engine was built in the early 1970s. I have another 55 with the original box that is dated 1975 and this engine is just a bit earlier, I believe.
A video will be forthcoming.

Here’s a short video. Enjoy!

https://youtu.be/cdqKtY9bv7U