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Oldjimturbine

Octura and du-bro nitro fuel

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Hello.  I have no literature on the ohlsson rice carbs on the octura or du-bro engines, and  was wondering if there was any data on the recommended fuel mixture, or company sold fuel recommended.  Also any data on whether the engines failed due to the glow plug and running on nitro?

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Not sure I can help much as I don't have any O&R's with either of those carbs, a few years ago I nearly got a glow converted engine with the Octura carb, but the seller messed me about (and presumably several others as their ebay account soon got terminated).

I've only seen two O&R boat engines with the Octura carb so they must be quite rare. Likewise the O&R with the Du-Bro carb is just as rare.

Presumably a similar mixing ratio for glow fuel would be required, what do the modern glow engines of similar size use? Just be aware of early O&R compact engines with the plastic bearing housings as they could potentially react badly with some fuels/oils.

 

The only O&R's that I aware of having problems with glow conversion & nitro fuel were the much older & smaller Ohlsson model engines that were commonly used in model planes, broken con-rods & cylinder head failure being two problems with these engines.

 

David

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Hello.  Thank you for the info, I might be able to get a shark manual that might provide answers, and when I get it, I will share the info if you want.  I also might have a stripped down ohlsson engine with that carb if you want it.  I will compare it with the dubro carb I have, and see if there is a match.  Maybe someone crashed the heli, and from what I read, I guess they crashed better than they flew.  I saw a video of someone who must have been an expert, fly one for almost 10 minutes.  The one I have has a spark plug hole, I'm guessing they used the same carb for the petrol versions?

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I compared the carb with the dubro carb on the rc helicopter, and they look identical to me.  Someone may have stripped the ohlsson rice engine and modified it for an airplane, and when I purchased the engine, possibly at some point the glow adaptor if that's what it's called, was removed prior to the sale.

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Very few O&R's that have been used for RC models seem to have been converted for glow, the adaptor/bushing for using 1/4" glow plugs in the 10mm or 14mm cylinders aren't very easy to find, seems people either have to machine one to fit or find somewhere selling them.

I did however find one place that has some ready made adaptors/bushings that may or may not be suitable;

http://www.thunderboltrc.com/index.php?main_page=index&cPath=100_183

 

As these Helicopters aren't exactly common (working ones even less common) it may be a good idea to contact the owner of this one on youtube for advise, reading the comments it seems they aren't a big fan of O&R engines though.

 

There is also an RC airplane that someone on youtube has built using an O&R chainsaw engine, it runs with the original carb & magneto ignition too.

 

I do have a couple of O&R's with different carbs that were used in model boats, maybe I should add some pictures if anyone is interested, one is a K&B and the other maybe a Waltron, both are standard spark ignition & air-cooled. There was also a heavily modified O&R with an Irvine carb sold recently on ePay.

 

I now have (thanks to Webhead) a Tillotson HU carb that O&R/AEP used on a weed wacker, I plan to adapt one of my spare engines to fit this carb and will update the thread here with my progress;

 

David

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Thanks again for the info.  There is someone very interested in purchasing my helicopter, says he has Hughes and looking to get sharks to.  He says it runs good, recommends adding a gyro, and the only thing is to think in advance when flying, and his works fine with the o&r.  I have the Instruction manual, and read an interesting part about the engine.  It read the top would come off some of the early engines, and to send it back to dubro for an upgrade.  The fix was to file the top of the head.  I will try to add the instructions to this post if anyone is interested.

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I made a big mistake.  The note was mentioned in the Hughes 300 helicopter manual, which was before the shark, according to the dates I am looking at.  I'm looking at the note as I type, and the top end came off, they don't mention what the top end is, but I'm guessing it's the adaptor.  They wrote that the problem was the piston skirt.  The fix was to remove the piston and file off the high(shiny spots).  The other manual I have is a shark  iced with a shark 60 manual, which has no note about the top falling off, so Im guessing that was no longer a problem with the later models, though I'm not sure if there were any later model o&r engines in 1973 or 1974, I have to read about what you guys wrote about the later engines to find out.  Maybe they tested and filed before sending out the product.

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