McCoy .049 diesel prop?

Ok guys, I have had a bunch of McCoys thru the years, but not this particular little puppy. Recently acquired, very clean. I assume something in the area of a 7-4 or so as a start?

Thanks,

Try a 6x5 or 7x4, and be very, very afraid of overcompression! These engines have a reputation (including the only one I ever owned) of having weak cranks.

If the exhaust is dark, lighten up on the compression!! NOW!!!

They don't make 'em like they used to. And that is a GOOD thing!!!

Put it on the display shelf, sell it to a collector, buy a PAW 55 1bb and be a happy camper.

>Try a 6x5 or 7x4, and be very, very afraid of
>overcompression! These engines have a reputation (including
>the only one I ever owned) of having weak cranks.
>
>If the exhaust is dark, lighten up on the compression!!
>NOW!!!
>
>They don't make 'em like they used to. And that is a GOOD
>thing!!!
>
>Put it on the display shelf, sell it to a collector, buy a
>PAW 55 1bb and be a happy camper.

Ron B.
F4Fguy

What Larry said.

One of the best .049s I ever had was a McCoy .049 Deisel.

One of the worst .049s I ever had was a McCoy .049 diesel.

If you really want to use it,stay on the small side of the prop range (6-3 6-4).You really do stand a good chance of losing a crank if you over load or over compress it.

>>Try a 6x5 or 7x4, and be very, very afraid of
>>overcompression! These engines have a reputation (including
>>the only one I ever owned) of having weak cranks.
>>
>>If the exhaust is dark, lighten up on the compression!!
>>NOW!!!
>>
>>They don't make 'em like they used to. And that is a GOOD
>>thing!!!
>>
>>Put it on the display shelf, sell it to a collector, buy a
>>PAW 55 1bb and be a happy camper.
>
>Ron B.
>F4Fguy
>
>What Larry said.
>
>One of the best .049s I ever had was a McCoy .049 Deisel.
>
>One of the worst .049s I ever had was a McCoy .049 diesel.
>
>If you really want to use it,stay on the small side of the
>prop range (6-3 6-4).You really do stand a good chance of
>losing a crank if you over load or over compress it.
>
>Ron B.

Naw, It is going on a Mackey "Redwing" because that is what he used on the original model. All my other diesels have been above .049s and I have a whole drawer full of them.
I know about the weak crank, also that they (like the OK Cubs) used a O-ring as a compression seal and this goes kaflooey after a bit of running.
It ain't a PAW, or any modern motor but it is cute and I hate to just let it sit- thanks guys.

J

While the topic is small Americian diesels, can someone tell me the collected wisdom on OK 0.074's (diesels). I have one now in a 36 inch span Free Flighter. Doesn't have a lot of power. Tried a 8 x 4 and it's overloaded, but a 7 x 3 at least flies the model. The motor was new when I bought it but the o-ring may need replacing just due to shear age. I love the look of it and it's quite different from the Mills, D.C.'s, Paws used down here (in OZ) for sport FF.

What props would be appropriate?
Any nasty habits, like breaking cranks?
What fuel? Does it need amyl nitrate substitute?

If I remember correctly, GMA said (on SMALLnet) that the McCoy .049's with the square opening in the crank were the ones that broke easily, the ones with the round opening were stronger. Anyone else remember this?
Another thing GMA stressed in general about old diesels was to not under prop them.

As for the OK .074, never heard anything bad about them. Had one for about 40 years but only ran it a couple of times. Gave it back to the friend I bought it from so he could recapture a bit of his youth with it.

> If I remember correctly, GMA said (on SMALLnet) that the
>McCoy .049's with the square opening in the crank were the
>ones that broke easily, the ones with the round opening were
>stronger. Anyone else remember this?
> Another thing GMA stressed in general about old diesels was
>to not under prop them.

Ron B.
F4Fguy

Mine is in it's box right now with it's broken round port shaft beside it.This is a very early engine.The later ones(even the round ports)had bigger diameter shafts.The comment re underpropping is valid if you are looking for the best performance,but for saving shafts,small prop =low load =low torque requirement =longer shaft life.

>>>Try a 6x5 or 7x4, and be very, very afraid of
>>>overcompression! These engines have a reputation (including
>>>the only one I ever owned) of having weak cranks.
>>>
>>>If the exhaust is dark, lighten up on the compression!!
>>>NOW!!!
>>>
>>>They don't make 'em like they used to. And that is a GOOD
>>>thing!!!
>>>
>>>Put it on the display shelf, sell it to a collector, buy a
>>>PAW 55 1bb and be a happy camper.
>>
>>Ron B.
>>F4Fguy
>>
>>What Larry said.
>>
>>One of the best .049s I ever had was a McCoy .049 Deisel.
>>
>>One of the worst .049s I ever had was a McCoy .049 diesel.
>>
>>If you really want to use it,stay on the small side of the
>>prop range (6-3 6-4).You really do stand a good chance of
>>losing a crank if you over load or over compress it.
>>
>>Ron B.
>
>Naw, It is going on a Mackey "Redwing" because that is what
>he used on the original model. All my other diesels have
>been above .049s and I have a whole drawer full of them.
>I know about the weak crank, also that they (like the OK
>Cubs) used a O-ring as a compression seal and this goes
>kaflooey after a bit of running.
>It ain't a PAW, or any modern motor but it is cute and I
>hate to just let it sit- thanks guys.
>
>J
>
>
>
Jake, I built that Mackey Redwing and used the motor that he used, a Frog 049 diesel. I wish I still had that motor. You wouldn't want to copy your plans would you.I would of course pay all costs.
Bare has the monster but the Redwing was really a great little model. Actually it wasn't that little.
Dennis

I don't have the full-size plans, just the mag article with the reduced size plans page- so you'd have to enlarge them. I'd be happy to copy them for you though. I've been trying to get Bare to add this one to his plans list, but I don't know when he's going to get around to it. You're right, it is a nice ship and far larger than the typical 1/2As of that era (early '60s).

>I don't have the full-size plans, just the mag article with
>the reduced size plans page- so you'd have to enlarge them.
>I'd be happy to copy them for you though. I've been trying
>to get Bare to add this one to his plans list, but I don't
>know when he's going to get around to it. You're right, it
>is a nice ship and far larger than the typical 1/2As of that
>era (early '60s).
>
>J

Thanks Jake but I have the article. I lost my set of plans a few years ago and was looking for a replacement. Guess it's a trip to Kinko's
Dennis

You can get new O-rings in a variety of space age materials from:

[email protected] 1-800-220-4242 or www.smallparts.com

They have both Buna-N and Viton. I would expect the Viton to last forever.

Would it be better to use something like a 7x4 prop (less compression needed to get it to fire) or a 6x4 (less load on the crank but higher compression needed to get it to run)? I was wanting to run mine too.