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

I figured out how to run my shiny new Jensen 85 without blacken boiler house or turn into burnt marshmallow paint!
  All kidding aside, I have been wanting a way to run my small steam engines on compressed air (at times)
  I purchased this pump off Amazon for about $26 shipped, I thought it was going to be about 2x the size of a computer mouse...its Really about 1/3 the size of a 2 slice bread toaster!
  I am ok with that as long as it works, the best feature is the knob on the top is the air control, I can get from 0 RPM up to approx 400 RPM out of it with approx 70 RPM the slowest it will run reliable on the new Jensen 85, perhaps it will do better when the Jensen is run in.
  I hooked it to the Wilesco D3 first and it would try a little but Not run, then to my satisfaction it runs the Jensen quite nicely! This does show the superior quality of the Jensen well (IMHO) I do plan on fix the D3 steam ports (as Bruce suggested) and it will be interesting to see if that gets it working on low PSI.
  The pump is only rated to put out 2.32 PSI, I did not know that when I ordered, I was hopeful it might do at least 3 PSI but I think it will be satisfactory for my use. The "throttle" feature is big fun! I have all 4 ports connected to the Jensen 85 but it does run on only 1 port as well, so it must be pressure I need more than volume.
  I am curious now if the pump will run my largest engine (Wilesco D20) and I will make a test of that soon. I have a feeling it may as the larger piston is an advantage on low PSI. I also need to make a proper air fitting to fit the boiler, right now it is just tape wrapped around aquarium fitting and wedge fit like a cork.
  My Jensen 85 is ticking merrily away as I type and I need to go give it some more oil.

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This one goes as a Big shout out to Bruce! I purchased this D45 Months ago (very early in my Steam Acquisition Disorder)
  I am embarrassed to admit I have Never fired it!
  We where in the thick of Covid and Nobody had steam oil! I Finally ordered from a vendor that I believe Jan recommended, all the way from Germany.
    Waiting 6 weeks for steam oil, this engine was placed on a shelf and more engines blocked it from view...until tonight!!
   This D45 runs even better then the not yet run in Jensen 85! I am getting apox 675 RPM out of her at max pump pressure and she will idle down so slow it sounds like a Grandfather clock ticking! I can see the individual power strokes on the flywheel as it ticks over. This is a testament to Bruce's work and also to the more efficient design of the slide valve engine. Bruce electrified this engine and also did several other mods to it, she runs beautifully, and now that I have seen her run on air, I plan to Steam her tommorow. Thanks Bruce!!
   
Side Note: this engine runs about 6% faster in the anti-clockwise direction, I have long suspected Wilesco engine steam chests are not "always" mounted in the perfect "center" of slide valve, this is one reason I wanted the air pump, I think it's great for performance tuning, without the hiss of steam and no chance of getting burned, I can loose the 2 screws and shift the steam chest back and forth in the clearance of the holes and see if I can get the engine to run the same speed in both directions....Or possibly bias even further in one direction for max power output? I love to experiment.
  This test has me thinking the D20 will run on 2.32 PSI as well.

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Looks like you´re having a ball experimenting with that new airpump Ben

I also use air a lot for testing/adjustments, as you mention the cold engine is a neat boon during that phase...and much faster than raising steam.

Any engine that will run on 2.32 psi is a pretty well tuned engine,I run a fair amount of engines on my aquarium pump next to my chair in the evening.

Any engine that will run on 2.32 psi is a pretty well tuned engine,I run a fair amount of engines on my aquarium pump next to my chair in the evening.

So true, with a bigger compressor almost any engine can be made run if you give it enough air, I find any engine that doesn't want to run on my air brush compressor with the built in regulator needs a bit more attention.

I had this D100e kit unbuilt, and had not yet decided how I want to modify it, so today it occurred to me to just assemble it stock first to see how it runs compared to my vintage D5.
  The D100e is really just a kit Version D5 with a different color paint job and a small generator + some LED bulbs and a few other electronic parts to do some simple experiments.
  I have watched a YouTube video of a young teen that built one of these and  video was his first Steam and his D100e did NOT want to run on Steam!....now that I have built mine, I may know why.
  All built stock, it did not even want to try to run on 2.32 PSI, I noticed the current pivot pin spring is much more stout than vintage unit, so I switched to ink pen spring for aquarium low pressure, this gave a VERY sleepy low idle and no amount of adjustment helped. It was so poor I began to suspect my pump was failing but I took the cylinder off and gave the port face a swipe on 800 grit sandpaper on flat glass, this showed a high spot in bullseye pattern around the pivot pin tapped hole, the brass looked displaced almost like the tap drill is one size to small so the tap is possibly pushing the soft brass high, what ever the cause, the sandpaper/glass treatment had it dead flat in under a minute.
  That's all it took to have it humming merrily away in photo. I think it may have run on steam pressure but poorly. I love this little pump for tuning!
  I am happy Wilesco is trying for close to 100% thread in soft brass, but they may need to add a small flatten step to port face After tap operation.
  I will build up the included generator now that the engine is doing well.

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My low cost D105 ebay find showed up today, much to my pleasure it is unfired and survived shipping with zero damage.
  I had to try it on my new air pump and it came to life with authority, as I have mostly run occilator type engines on the pump lately the advantage of a slide valve engine is obvious. It does run about 30% faster with the govenor disconnected, I have often thought Wilesco runs the spring belt tension a little high. I stretched the spring belt just a little and this helped bring the speed up with govenor belted, however the joint of the spring belt now looks lumpy as it travels, this doubled area of a spring belt joint is a "hard" spot so it does not travel as smoothly. I may make up a black o-ring belt to see If I can get a smoother operation out of this feature.
  I am having second thoughts about cutting this engine up for parts, original plan was to harvest the cylinder/valve/rod group for a power upgrade on my Mamod Roadster build and use the boiler/base to power one of my kit steam engines...

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