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Engine basics => Engine set up tips => Topic started by: wwwarbird on May 19, 2015, 09:28:03 PM

Title: OS .29 w/rear NVA?
Post by: wwwarbird on May 19, 2015, 09:28:03 PM

 I've recently acquired this OS.29 that has a rear mounted needle valve assembly. It's in excellent condition and doesn't appear to have ever been run or mounted. I don't expect that it's a super rare find, but I'm not sure if I've ever personally seen one. Can anyone here fill me in on the vintage? Any other information on this engine would be appreciated as well.

 Thanks! H^^

Title: Re: OS .29 w/rear NVA?
Post by: Robert Zambelli on May 19, 2015, 11:57:08 PM

Hi, Warbird.
I have a number of steel finned OS engines but I've never seen one like yours.
It might have been converted by a private individual, maybe to mimic the bathtub-intake Fox 29R.

  Bob Z.

Title: Re: OS .29 w/rear NVA?
Post by: rustler on May 20, 2015, 01:33:15 PM

O.S. factory item. O.S. 29-X. Should contain some special parts, - can't remember off hand. Nice.
Sometimes called Custom-X?
Anyone got a 35-X available?

Title: Re: OS .29 w/rear NVA?
Post by: wwwarbird on May 21, 2015, 10:49:20 PM

Quote from: rustler on May 20, 2015, 01:33:15 PM

O.S. factory item. O.S. 29-X. Should contain some special parts, - can't remember off hand. Nice.
Sometimes called Custom-X?

 Any idea about what year it would have been introduced? How long they were made? Just curious...

Title: Re: OS .29 w/rear NVA?
Post by: Dane Martin on May 24, 2015, 04:37:03 PM

1961 29-III X would be my guess based on the plug location. It's a max-III and the one I got is a max-II mine is a 1957 29 II.
hope this helps

Title: Re: OS .29 w/rear NVA?
Post by: frank mccune on May 25, 2015, 05:46:02 AM

     Hi:

      I concur with Dane.  I think that it is a 1961 .29III X.  Made for only one year.

      Of course I have been known to be wrong in the past. Lol

                                                                                                              Good luck,

                                                                                                              Frank

Title: Re: OS .29 w/rear NVA?
Post by: rustler on May 26, 2015, 01:37:57 PM

Peter Chinn in the Brit. mag Model Aircraft reviewed this motor, maybe over a couple of issues.
I think one feature was a couple of small holes in the piston each side of the wrist pin to allow oil to seep through the holes and lubricate the cylinder walls. And maybe a special rod.
Another identifying feature is that the exhaust is not tapped for silencer fixing. If/when I find the mags, and hoping I remember, I'll post details.

Title: Re: OS .29 w/rear NVA?
Post by: wwwarbird on May 26, 2015, 06:03:58 PM

 
 Thanks for the info guys, interesting stuff. y1

 For Sale: http://stunthanger.com/smf/index.php/topic,39470.0.html

Title: Re: OS .29 w/rear NVA?
Post by: Clint Ormosen on May 27, 2015, 06:09:49 PM

Oh yeah, super rare.  D>K

(Sorry Wayne. Couldn't resist. I tried.)

Title: Re: OS .29 w/rear NVA?
Post by: wwwarbird on May 28, 2015, 06:08:07 PM

 Huh? I don't see a rear NVA on that one Clint. D>K

Title: Re: OS .29 w/rear NVA?
Post by: Dane Martin on May 28, 2015, 06:11:45 PM

Clint,
I may be wrong, but yours looks like a 1959 os 29-III
to me. Basically the same thing.
Sorry to intrude guys, but I'm a huge OS engine nerd! It's all I use. Except Cox 049's of course!

Title: Re: OS .29 w/rear NVA?
Post by: Clint Ormosen on May 28, 2015, 09:49:06 PM

Quote from: wwwarbird on May 28, 2015, 06:08:07 PM

Huh? I don't see a rear NVA on that one Clint. D>K

Nah, it doesn't. Same engine minus that feature. Just hassling ya.