McCoy DuraGlo .049 Diesel

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McCoy DuraGlo .049 Diesel

Postby tag » Tue Sep 19, 2006 2:00 am

I would like to get some information on the McCoy DuraGlo .049 diesel.
What prop and what fuel do I use in this little engine? What sort of performance should I expect? Any other tips?

Thanks
Tom
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Postby gossie » Tue Sep 19, 2006 2:17 am

Any model diesel will start and run well on an equal mix of kerosene, castor oil and ether.
There are sure to be mixes to make it go harder, you will need to experiment, but the above is a simple no nonsense mix that works.

I would start off with an 8x4 prop. to get it going, and probably a 7x4 would get it reving nearer it's peak BHP. Good luck. :D
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McCoy .049 Diesel

Postby Ken McClenahan » Tue Sep 19, 2006 8:55 pm

The instruction leaflet recommends a 6X4 propeller.

I think that was what I generally used when I was running them back in the early 50s but I do remember also using 7X4 propellers.
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Postby gossie » Wed Sep 20, 2006 1:03 am

6x4 prop. will get it right up to the max. BHP revs, about 11 to 12000.

Might be a bit hard to start on a very small prop----was yours okay, or better on the 7x4?

Does also depend what you wish to do with it also, I guess---duration, or fly for fun.
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McCoy .049 "D"

Postby diesel_don » Wed Sep 20, 2006 1:14 pm

McCoy as well as Herkimer OK Cub diesels used a synthetic elastomer "O" ring to seal the contra piston. In a 50 + year old engine, the "O" ring could have lost its sealing properties. Superior compounds have come along since then. IIIRC "Viton" is one & there are others. I've never replaced one but have been advised that creating a slight chamfer at the top of the cyl (Dremel, and be careful not to slip!), can help ease the new ring into place. I had heard the repro version, out recently has a traditional "fitted" contra piston. Hope this helps, Cheers; dieselsonlydon
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Postby tag » Wed Sep 20, 2006 6:26 pm

Thanks for all the replies. I'll try a 7*4 first and then maybe a 6*4 after I run it a bit.

What is involved in replacing this O-Ring? Is it something that I can locate locally or is there a source for the proper one?

Thanks
Tom
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McCoy .049 Dielsel

Postby Ken McClenahan » Wed Sep 20, 2006 8:50 pm

I never had any problems replacing the O ring but the life of the original was very short (maybe six months after the engine had been run). Just unscrew the head and pop the contra piston out. The real problem is finding a replacement O ring. I would start looking at Ace Hardware and experiment with whatever I could find that looked like it was about the right size.
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Postby gossie » Thu Sep 21, 2006 12:51 am

I found the "road test" of the McCoy in Aeromodeller October 1953 magazine today, and it does make mention of the O ring showing early signs of wear.

It peaked at 12500rpm and turned wooden props as follows-------

9x4= 5700, 8x4= 6700, 7x4= 8000, 6x4= 11650, 6x3= 12250.
Modern APC props. being thinner than the old wooden ones would also raise the revs I should think.

Fuel mix was, Kerosene 40%, Castor oil 25%, Ether 32.5% and Amyl Nitrate 2.5%.

With it unloading in the air looks like 7x3, or 6x4 is the prop. to use for competition, larger for fun flying would do the job.

Amyl Nitrate is very hard to get these days, but it should run well just bringing the Ether up to 35%.

I know Ace Hardware in USA, as have bought plenty off them over the years, when over your way,and "Wally World", or an auto spare parts store will have them too. Good luck. :D
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Postby tag » Fri Feb 23, 2007 1:15 pm

Who here has changed the O-ring on the contra piston on the .049 Duraglo? What size did you use? I matched up and bought some 5/16*7/16/*1/16 Viton O-rings but can't get them in without slicing the sides off when installing. Is there some trick or is the size that I have wrong?

Thanks
Tom
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Postby Frank Klenk » Sun Feb 25, 2007 7:59 am

Tom

Make sure you lube the O ring well. If it still cuts try a smaller O ring and stretch it over, that will reduce the actual diameter of the O ring material. I just rummage through my O ring boxes till I find one that works. :)

Frank
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