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Another Original Deezil Runs!

Old 12-16-2009, 04:59 PM
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Default Another Original Deezil Runs!

Hi guys. (Any gals? No? I didn't think so...)

Anyway, I posted Original DEEZIL Runs on this forum on September 21, which related my friend Luitpold Fiess's success in running an original Deezil. He made a new piston and put two o-rings on the contrapiston in order to accomplish this.

Now I have completed rebuilding my Deezil. New cast iron piston and contrapiston. New aluminum connecting rod and steel wrist pin replacing the brass original parts. New bronze crankshaft bushing. In one of the attached pics, parts in upper right are originals, in lower right, the replacements. Crankshaft bushing at the left is the original; new one is in the crankcase.

The original parts are of reasonable quality- apart from the poor choice of using brass. The steel cylinder is not hardened, but is adequate to show no excess wear after a couple hours running. I lapped the cylinder to be sure that it was round, but it was good enough that I probably did not improve it. Interestingly, it had a few ten thousandths taper. It is also turned from a single piece of steel, rather than being made from tubing to which the mounting flange is brazed, as on later Deezils. The crankshaft, web, and crank pin are three pieces, pressed and brazed together. The job is nicely done and of adequate strength for running the engine. In later Deezils, the assembly is crude, without brazing, and too weak for its assigned task. With my engine, although most parts quality was good, fits were very poor, specifically with regard to piston, contrapiston, and crankshaft bushing.

The engine now runs very well! Using Davis Diesel fuel with extra castor oil and a Zinger 10 x 4 propeller, I get 7,100 rpm. The engine running in the picture below has a spinner nut because I use an electric starter, contrary to usual recommendation. This allows a lower initial compression setting, which seems to me a good idea if one is unsure of an engine's robustness. Also the Deezil is rather short-nosed, leading to a bruised flipping finger if one is as poorly coordinated as I! . (Ok, so here is the obligatory disclaimer: If one uses an electric starter on a diesel, it must be done with great care to avoid engine damage in case of hydraulic lock.)

Now here are a few notes of possible interest. Bore of my original Deezil is 0.482 in and stroke if 0.700, giving a swept volume displacement of 0.128 cu in. Port timing is 104 degrees duration for exhaust, 76 degrees for transfer, and 126 degrees for intake. This compares to 127, 113, and 102, respectively for the Gordon Burford and Schroeder replica Deezils. Performance is similar among the three engines. One might conclude that port timing is not a critical matter among slow-running long-stroke, side-ports. Details of the scavenging geometry are different among the three.

No one seems to know about origins of the Deezil, that is, before it was acquired by the Winston brothers of the Gotham Hobby shop, New York City. However it is certainly based on the Swiss Dyno (see pic), generally regarded as the first commercially successful diesel hobby engine. External appearance and internal arrangements, including scavenging, are quite similar. However, the Dyno's port timing was not copied by the Deezil's designer. Dyno has an exhaust duration of 123 degrees, transfer, 96 degrees, and intake of 88.7 degrees.

Also attached below, just for the fun of it, is a copy of an original Deezil ad. Gotham ran hundreds-likely thousands-of ads in hobby magazines, Popular mechanics and Popular Science, and comic books in the late 1940s and well into the 50s. Remember them?

Too bad the Winstons made such a mess of it! If decent quality had been maintained, the Deezil would have been a nice engine. Mine certainly is - now!

Regards. And Merry Christmas! -Gary
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Old 12-16-2009, 05:21 PM
pe reivers
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Default RE: Another Original Deezil Runs!

Nice job!
Old 12-16-2009, 07:40 PM
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Default RE: Another Original Deezil Runs!

Nice work Gary-another derelict Deezil restored to working glory! I must say that original rod little end looks decidedly flimsy! Your comments mirror what i've read about another equally notorious engine the GHQ ignition engine. IIRC the very first ones were quite well made-but as pressure grew to increase sales production was stepped up and/or subcontracted out with a massive reduction in fits and quality-with the result that it soon acquired a reputation as a 'lemon'. The same old story-an engine needs decent design and porting, appropriate material selection, and the correct component fits to be a success-aeromodelling is littered with the carcases of engine disasters that got just one of the three critical parameters wrong......let alone all three

Old 12-18-2009, 08:28 PM
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Default RE: Another Original Deezil Runs!

Thanks Pe and Chris! WRT con rod lower end, I think that it need not be very thick around the perimiter because stress is always directed toward the piston, ie, during both power and compression stroke. I expect that when the bearing surface wears, its always on the top side. Is this correct?

I kinda overdid this project by bronze bushing both ends of the rod and putting an oil hole in the lower end. On a DEEZIL??? Um, yes. But this was my most ambitious engine rebuilding project so far and an opportunity for learning. Which is what its all about for me. Also the first time I used my new Chinese mill/drill, an adventure in itself. I had heard that with Chinese machine tools, one gets a kit of parts from which one can build a servicable machine. A bit of an overstatement, in my experience, but esentially true... I was also warned that it takes much more time to set up a project on a mill than a lathe. And that it certainly true!

WRT the GHQ engine, as well as other slags, it would be fun to rebuild some of them. Not just to see how well they might run, but also for the reaction from other flyers at a SAM meet to see a GHQ or Thor or Buzz or Judco or Ram pulling a vintage airplane into the air!

I do have it on my agenda to fly the mighty Deezil. Maybe in the spring.

Regards. -Gary
Old 12-19-2009, 07:03 PM
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Default RE: Another Original Deezil Runs!

ORIGINAL: gmedson
WRT the GHQ engine, as well as other slags, it would be fun to rebuild some of them. Not just to see how well they might run, but also for the reaction from other flyers at a SAM meet to see a GHQ or Thor or Buzz or Judco or Ram pulling a vintage airplane into the air!
I had a Thor once, but it had already been run. Actually it had been worn out and had nothing left. It was missing the points so probably had been run on glow. Someone gave it to me along with a worn out O&R .23.

I have never had a GHQ, but I understand many had trouble with them because they were set up to run clockwise.


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