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Author Topic: O & R engine  (Read 281 times)

Offline Leester

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O & R engine
« on: February 08, 2020, 12:10:05 PM »
I have a couple O&R engines I got from a former co-worker, they were his Dad's. They have no size markings on them and his dad has passed away so the only clue I have is when I took the front engine cover off it was stamped inside OR 23  29  UP. The old prop was a TF 7" wood prop. The one I'm working on has excellent compression what fuel and glow plug wood be best ?? I have a Thunderbolt in it and how does the head come off ??  What prop should I use I have a 9-4 on it.
Leester
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Offline Dennis Toth

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Re: O & R engine
« Reply #1 on: February 08, 2020, 04:08:44 PM »
Leester,
The O&R's have a pressed in head that is not removable. It should run fine on normal glow fuel 5 - 10% N with at least 25% oil, should have mostly castor particularly for the first few runs. Any normal glow plug will work fine. I would say for bench run the 9-4 will be fine, just don't go crazy lean. If you are going to fly the engine, then for the 29 I would go with a 9-6 for the 23 cut down the 9-6 to 8 1/2. Make sure you have the connecting rod free on the piston side. I have used a heat gun set to high. Best to heat - let soak for 15 - 30 sec, then heat again. Once it is moving free use some after-run oil to keep it free and a drop or two of fuel will get it smooth. Also, some of the O&R's had a single drum bearing on the crank, again use some heat and penetrating oil to get them lose then the after run.

Best,    DennisT

Offline Leester

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Re: O & R engine
« Reply #2 on: February 08, 2020, 05:11:11 PM »
Thanks for the info. I was going to order some 5 or 10  % nitro & 29% castor for a Fox 35 so I'll just get 1qt 5% and 1 10%. As I said I don't know if there 23 or 29's . I would love to fly them. I have a Zilch X-Pendable I was thinking of IF they run OK ?? I'll see about the connecting rod and the bearings. Again Great info..!!
Leester
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Offline Brett Buck

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Re: O & R engine
« Reply #3 on: February 08, 2020, 05:36:29 PM »
I have a couple O&R engines I got from a former co-worker, they were his Dad's. They have no size markings on them and his dad has passed away so the only clue I have is when I took the front engine cover off it was stamped inside OR 23  29  UP. The old prop was a TF 7" wood prop. The one I'm working on has excellent compression what fuel and glow plug wood be best ?? I have a Thunderbolt in it and how does the head come off ??  What prop should I use I have a 9-4 on it.

   As noted, the head *does not* come off, at least not intentionally. These engines are low-RPM "chuggers", 4" of pitch is far beyond them. 6-7", maybe a 9-6. Performance is low.
   
   The others have warned you, but blowing the entire cylinder off of them at high RPM is a distinct possibility. I did it with a 23 Sideport. You can JB-Weld it back, but that's not going to make it any stronger.

For fear of incurring further wrath, I wouldn't expect either engine to be much good for any stunt plane, or more than lazy sport flying, they are very weak for their dimensions, even compared to other engines of the era. They are *light* for their displacement, but still vibrate a lot, so you have to build the airplane pretty stoutly - by which, the 23 might have the power of a weak Max III 15, but still has to be built to take the vibration of a 29. A Fox 29 (the one built into a Fox 35 case) will blow either one out of the water, in terms of power, same with a McCoy 29 Redhead.

    Brett

Offline Leester

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Re: O & R engine
« Reply #4 on: February 08, 2020, 05:51:50 PM »
Thanks Brett !!! I think you saved me from a lot of wasted time and $. I didn't realize they were that crappy !! lol Oh well I'll try to get it running just to say I did. It's still fun to mess with !!
Leester
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Offline Brett Buck

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Re: O & R engine
« Reply #5 on: February 08, 2020, 05:59:00 PM »
Thanks Brett !!! I think you saved me from a lot of wasted time and $. I didn't realize they were that crappy !! lol Oh well I'll try to get it running just to say I did. It's still fun to mess with !!

   Crappy is a bit strong, but they really weren't "with it" at the time they were made, they were sort of throwbacks to pre-war ignition engines for sport FF. Teh rotary valve versions are also *much* better than the sideports - and at least they ran forwards most of the time!  Some pretty remarkable advances were made in the era from 1946-1960, O&R were not the leaders.

    Brett

Offline Andrew Hathaway

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Re: O & R engine
« Reply #6 on: February 13, 2020, 04:26:12 AM »
I made the mistake of building a model for a O&R 33 red head ignition engine.  Never got it to run right, consistently on the plane.  Biggest issue was simply not enough power.  The model has an OK Mohawk 29 ignition engine on it now, which works a lot better.  Only trouble is the OK made the model nose heavy.  I wouldn't expect a CL model with an O&R anything to do much more than level laps.  My experience it was like trying to fly a sick 1/2a.  In lieu of the vomiting smiley, please accept this applicable smiley that nearly conveys the emotion.  HB~>

Offline Dennis Toth

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Re: O & R engine
« Reply #7 on: February 13, 2020, 10:29:46 AM »
Andrew,
What prop, fuel, ignition type (i.e. conventional or transistor) and the ignition advance did you use with the O&R? Many times with ignition you need to get the points set with the correct advance which might require a rather strong flip to start. If you are at TDC or later you will be low on power. Should have been able to turn something around a 9.5 - 10x6 prop open exhaust at 9200 ish rpm.

Here's a review on the O&R 33 on glow but still interesting.   http://sceptreflight.com/Model%20Engine%20Tests/Index.html


Best,   DennisT
« Last Edit: February 13, 2020, 11:39:13 AM by Dennis Toth »

Offline FLOYD CARTER

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Re: O & R engine
« Reply #8 on: February 13, 2020, 01:52:56 PM »
What you have is a later model O&R 29 front rotor.  The later models have the separate aluminum head (staked on) and the larger exhaust opening,. I have used many of them in the distant past.  I used a 10-5 wood prop and 10% nitro fuel with at least 25% castor oil.  You will not be happy with the stock needle valve.  Too touchy. 
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 Staying old is hard"
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Offline Andrew Hathaway

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Re: O & R engine
« Reply #9 on: February 14, 2020, 04:39:48 PM »
I tried a variety of props in 9-10" diameter, different brands and pitch.  Didn't seem make much difference.  Timing, fuel, and the rest of the system is/was fine, as everything is the same on the Mohawk, which runs like twice the engine. 

Worse yet I've got a blue head 29 glow that shakes like crazy, and a pair of sideport 23's that are absolutely charming engines to work with, but not remotely practical.  None of them would win an arm wrestling competition against a decent, 40 year old .15.

After the O&R, I went as far as to acquire an ignition Forster 35, but the Mohawk worked well enough to figure out I wanted to go bigger.  Built a Humungus with an Anderson Spitfire, and haven't looked back.  The Vampire makes a great wall-hanger, so it wasn't a complete loss.  ;D


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