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i guess the prop and spinner will just have to deal with it like they do with all the sloppy D shaft keyed prop hubs out there... with some of those you can get 20 deg. of slop easily. poor props and spinners... maybe you could loan your caliper to those manufacturers. |
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Not to interfere, but normally woodruff keys have a near press-fit. It is very rare that I can just turn the shaft 180 degrees to make the key fall out, and usually I need pliers to pull them out with more than a little bit force.... And that is just my experience of 25 years on electric motors, that do not have torque pulses.... A clearance of 0.07 mm, I would personally not trust to be honest. The Woodruff Key in my OS FS 91 Surpass II was also absolutely not a sloppy fit: I could pull it out with my fingernail, but I hurt my finger doing so and it did not fall out by itself.... Brgds, Bert |
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my webra is well used and despite the drop in fit of the key there is no wear or fretting of the crank or hub. and again, look at all the engines that have sloppy D keyed shafts, no problems with those either.
and woodruff keys are a different design and yes, they are often a very tight fit. |
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I see how people sometimes start engines, for example with an electrical starter motor, hammering on the crankshaft, In winter even modellers propulse there engine (read, as an air compressor to warm up) long before it will even start. Giving the original key other dimension than these original left the factory will be possible several ways, just as people can destroy the thread for the glowplug. We also talk about shims to lower the compression of a Webra, so the compression is some higher than (most) non european engines and even the Webra and all my own engines I handstart myself, these NEVER see an electrical starter motor, just in case to prevent mechanical deformations of all parts of the engine on other moments than it does its function as an IC combustion engine were it is designed for. Taurus Flyer |
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Taurus Flyer |
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I see a tight fit of the key in the crankshaft of my Webra Speed and a 'not so tight fit' in the prop drive(r)/(plate). No circumferential play.
Taurus Flyer |
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Thread OP
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Hi Guys,
Thanks again for all the information that you've provided me with (and also for the trouble that many of you have gone to in order to give me the dimensions of the keys and the needle valves that you own). I've purchased a needle valve from Germany (one of the ones with the very short knob - like the smallest of the three that were shown in the photograph in I Tobor's post #15). If it fits then great, if not then I'll either sell it on, or hang on to it in case of future need (I'm a bit of a pack-rat that way). I've also found someone who is selling six Webra needle valves from a defunct model shop and I'm going to get in touch and see if he can send me a photo of them so that I can try to find one with a longer knob (and the correct needle length). One last, quick, question - from what's posted above I gather that while the length of the needle might differ slightly that's not necessarily vital as long as it screws correctly into the spray bar (and of course isn't bent, etc.)? Is that correct? Thanks again for all your help, and based on the last few posts I hope that my bringing the subject up hasn't soured relations too much between you all! Cheers! Don. |
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Success Taurus Flyer |
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So if you place it, and it seats within two turns, most likely it will not do its job.... But I can't tell you how many turns the Original needle is supposed to have. Brgds, Bert |
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prop hub key solution
I have 5 Webra .61 's all have the key slot. I have lost many in the past. Here is the
solution and it is easy and you will have the item in your shop. Place the hub on the shaft, then line up the two slots, now take your many allen wrench (hex) keys laying around and fit the one that is just snug. Push it in for a fit. nowcut off the end to length. and you have it. Been doing this for many years. Works just great. |
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Thread OP
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Well, it looks like I have all the information that I need to fix those two problems. I like the idea of using an allen key as a key. Once I know what the correct size is (2.5mm?), I would be able to easily replace them in future. Nice idea surfmount!
Hopefully the needle valve that I've ordered will fit okay. It's part number is 1020/331, but I haven't been able to track down a list of carb part numbers and their application - so I'll just have to try it and see. Thanks guys Don. |
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