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Author Topic: OS 35 S  (Read 1143 times)

Offline Matt Neumann

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OS 35 S
« on: May 23, 2024, 04:51:53 AM »
I remember something about a weak link in the OS 35 MAX S engines being the connecting rod wearing out or something like that.  What was it exactly?  I have several "aftermarket" ones that dad had made as replacements that were supposed to be better. 
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Matt Neumann

Offline EricV

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Re: OS 35 S
« Reply #1 on: May 23, 2024, 06:29:30 AM »
If I remember correctly the lower end of the rod wasn't drilled for an oil hole and wasn't bushed sufficiently so they would wear out and get sloppy prematurely. The fixes varied from drilling and adding a bushing, adding an oil hole and or replacing with a Supertigre 35 conrod which fit and was super beefy in comparison. Guessing your pop had some machined up to his own preffered spec. I'm sure someone will remember in better detail and correct me, but this should get you started.

I have a Glenn Dye Max35S in a drawer somewhere that he chromed the sleeve and put the upgraded ST rod in... its never been run and I was saving it for a special classic build "someday". At this rate, someday probably isn't coming...
EricV
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Offline Matt Neumann

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Re: OS 35 S
« Reply #2 on: May 23, 2024, 06:36:28 AM »
Quote from: EricV on May 23, 2024, 06:29:30 AM
If I remember correctly the lower end of the rod wasn't drilled for an oil hole and wasn't bushed sufficiently so they would wear out and get sloppy prematurely. The fixes varied from drilling and adding a bushing, adding an oil hole and or replacing with a Supertigre 35 conrod which fit and was super beefy in comparison. Guessing your pop had some machined up to his own preffered spec. I'm sure someone will remember in better detail and correct me, but this should get you started.

I have a Glenn Dye Max35S in a drawer somewhere that he chromed the sleeve and put the upgraded ST rod in... its never been run and I was saving it for a special classic build "someday". At this rate, someday probably isn't coming...
EricV

I got one that Randy Smith did up new and it will be going in one of the Chipmunk planes that will be a tribute to dad since he built both.  The original Sig Chipmunk and the Super Chipmunk. 
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Matt Neumann

Offline Scott Richlen

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Re: OS 35 S
« Reply #3 on: May 23, 2024, 06:52:33 AM »
We used to run them with 11-5 (or 6) Rev-Ups which were a little large for the engine.  You could tell when the rod was going out as the engine would no longer hold a needle setting.  But they ran really well until you wore out their connecting rod.
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Offline Matt Neumann

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Re: OS 35 S
« Reply #4 on: May 23, 2024, 06:55:05 AM »
Quote from: EricV on May 23, 2024, 06:29:30 AM
If I remember correctly the lower end of the rod wasn't drilled for an oil hole and wasn't bushed sufficiently so they would wear out and get sloppy prematurely. The fixes varied from drilling and adding a bushing, adding an oil hole and or replacing with a Supertigre 35 conrod which fit and was super beefy in comparison. Guessing your pop had some machined up to his own preffered spec. I'm sure someone will remember in better detail and correct me, but this should get you started.

I have a Glenn Dye Max35S in a drawer somewhere that he chromed the sleeve and put the upgraded ST rod in... its never been run and I was saving it for a special classic build "someday". At this rate, someday probably isn't coming...
EricV

I am now remembering a lube hole being put in the bottom spot.  At least on the ones that dad had made up.
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Matt Neumann

Offline Matt Neumann

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Re: OS 35 S
« Reply #5 on: May 23, 2024, 07:02:47 AM »
Quote from: Scott Richlen on May 23, 2024, 06:52:33 AM
We used to run them with 11-5 (or 6) Rev-Ups which were a little large for the engine.  You could tell when the rod was going out as the engine would no longer hold a needle setting.  But they ran really well until you wore out their connecting rod.

An 11-5 or 6?  Wow.  I had a 10-6 on my Still Stuka.  I will have to try the 11s.  I got some (a lot actually, want some?) 11/6 and 10/6 wooden props I think from Eric Rule.  I think they are BY&O clones.
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Matt Neumann

Offline Dan McEntee

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Re: OS 35 S
« Reply #6 on: May 23, 2024, 07:03:25 AM »
Quote from: Matt Neumann on May 23, 2024, 04:51:53 AM
I remember something about a weak link in the OS 35 MAX S engines being the connecting rod wearing out or something like that.  What was it exactly?  I have several "aftermarket" ones that dad had made as replacements that were supposed to be better.

      The big end of the rod is supposed to wear faster. I got a couple of your dad's replacement rods years ago and would have to dig those out to see what exactly that made off. it's easy to just drill a couple of holes at about 4 o'clock and 8 o'clock, deburr the inside, and then chamfer the hole on the outside with a bigger drill bit.

  Type at you later,
   Dan McEntee
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Offline Scott Richlen

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Re: OS 35 S
« Reply #7 on: May 23, 2024, 11:40:50 AM »
Quote
I will have to try the 11s.

Just make sure you have the replacement rods with you when you do... ;D
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Offline Matt Neumann

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Re: OS 35 S
« Reply #8 on: May 23, 2024, 02:01:34 PM »
Quote from: Scott Richlen on May 23, 2024, 11:40:50 AM
Just make sure you have the replacement rods with you when you do... ;D

I plan too!  Actually some of the newer carbon props have about the same load as the older wooden props.  I probably plan on trying those.
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Matt Neumann

Offline Air Ministry .

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Re: OS 35 S
« Reply #9 on: May 23, 2024, 08:05:13 PM »
The Adamisin set up was a ' X ' onto the front face of the big end . Something like 1.2 mm radius . As in , if youd clamped two rods back to back , and drilled  ,youd have half a thing on each , as it were .
ALSO a nylon ' T ' pad , plugs in the crank big end end , to stop the rod walking aft . Lee Machine Shop does these .

We used to run OSes No Nitro , in the early 70s . No Problem . a 10 x 4 three blade Tornado , if you want to fly slow with a light plane , or a 11 x 4 , in the our stroke .
. So maybe half of it IS the slop for & aft , in the 30 & 35 . As in its a H 29 R rod , wot gets heck , so should be o.k. .



Multi Fit .



a 32 SX rod is bushed , and looks vaugely like it might fit perhaps .
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Offline Matt Neumann

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Re: OS 35 S
« Reply #10 on: May 28, 2024, 01:06:59 PM »
Quote from: EricV on May 23, 2024, 06:29:30 AM
If I remember correctly the lower end of the rod wasn't drilled for an oil hole and wasn't bushed sufficiently so they would wear out and get sloppy prematurely. The fixes varied from drilling and adding a bushing, adding an oil hole and or replacing with a Supertigre 35 conrod which fit and was super beefy in comparison. Guessing your pop had some machined up to his own preffered spec. I'm sure someone will remember in better detail and correct me, but this should get you started.

I have a Glenn Dye Max35S in a drawer somewhere that he chromed the sleeve and put the upgraded ST rod in... its never been run and I was saving it for a special classic build "someday". At this rate, someday probably isn't coming...
EricV

Guess what I found?  ST 35 connecting rods and yup they are beefier.  Brass bushings and an oil hole top and bottom. 
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Matt Neumann

Offline Juan Valentin

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Re: OS 35 S
« Reply #11 on: May 28, 2024, 08:08:56 PM »
                        I have this  OS.35S and since I had heard about the conrod problem I bought 2 Rods from Mr. Neumann for it but have never used it. It has a rod with an oil hole at the 7 o`clock position on the big end. My plan was to use it on a J. Kostecky  Talon stunter but have not built one yet. here is a pics of the engine.
                                                                                                                                         Juan


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Offline Air Ministry .

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Re: OS 35 S
« Reply #12 on: May 28, 2024, 08:43:55 PM »
these are like the THINg from Lee Machine Shop , to plug into THAT big crankpin bore , so sized to suit the rod , to prevent the rear face going aft , whilst running .

The Supre Tigre ROD used, is the dual ring .46 ( SHORT ) ' 21 rod , which is the 21-29 & 21 - 35 rod .  :P

just to up the anti , THAT is a .35 S T rod , and a Bri stunt replacement . So there ya go . dunno  if they need resizeing to fit the OS .



Hoo Kay , the OS is 6.35 crankpin , the ST 6 mm , both wristpins 5 mm . so the Big end needs reaming fitting ST rod to OS . MATE .  S?P H^^
« Last Edit: May 30, 2024, 11:45:07 PM by Air Ministry . »
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Offline Juan Valentin

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Re: OS 35 S
« Reply #13 on: May 28, 2024, 08:50:19 PM »
 Hello Matt
                      I will be saving your post in my docs. thanks.
                                                                                                             Juan
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