Historically not much discussion here about the OK Cubs?

rsv1cox Sat Sep 03, 2022 12:29 pm

Get no respect? Third tier engines? Not Ok?

So, my son called me from the flea market with a line on some engines. Mostly Ok Cubs he said. I was surprised at my initial negative - no, no, not only no but heck no. But he sent me a picture. $200 for the lot, down from $250. Are you kidding. Offer $40 for the Wasp. Seller wanted $50. No sale.

Historically not much discussion here about the OK Cubs? Mark_o11

I have all those engines pictured except the Wasp. Even ran one or two.

Does anyone have any love for the Ok's?

Ken Cook Sat Sep 03, 2022 3:10 pm

I myself never had any affection for the OK engines until about 6 years ago. First I will say there's a lot of neat models of the Cubs and understanding them is a feat in itself. One thing to recognize is that quality is all over the place. You have one that runs extremely well or it's just a complete turd. The OK's use radial porting and they're loud. The OK .19 in my opinion is one of the loudest engines I know of in a glow engine with spark ignition engines being the loudest. It's like running a Fox .59, it's obnoxious.

The OK .074 offers approx the same power as a Cox .049 Babe Bee. All noise and little power. The OK engines are very light which is very beneficial to the models such as the hollow logs. The .049's in the picture ( Not the ones with tanks) were the early .049's which shared the identical case as the .074. When the B model .049 came out with the red tanks, not the radial case A model, they changed the bolt pattern and made the case smaller.

Cubs like nitro and a lot of it and they're not afraid of it. A little shaft polishing goes a long way with these and you can get decent rpm's out of some of them. These are not easy engines to dismantle especially the versions with the magnesium backplates which look whitish and mottled nowadays, they can shatter just unscrewing them. The needle valves are ABSOLUTELY horrid on these engines. I found the Perfect replacement needles to work superior to the stock piece of crap offered.

I've found that these engines swing a bit more pitch than the Cox equipment. A 6x4 seems to work nicely on some of the .049's I have. I also found that the OK engines have had single porting bypass on the case and double.

I have several new in the box examples of the red and the gold .29's and .35's. I think these are some of the prettiest engines made. I have runners and new in the box examples which I just admire regardless of how they run. I just like knowing I have a great piece of history.

Oldenginerod Sat Sep 03, 2022 5:04 pm

rsv1cox wrote:Get no respect? Third tier engines? Not Ok?

So, my son called me from the flea market with a line on some engines. Mostly Ok Cubs he said. I was surprised at my initial negative - no, no, not only no but heck no. But he sent me a picture. $200 for the lot, down from $250. Are you kidding. Offer $40 for the Wasp. Seller wanted $50. No sale.

I have all those engines pictured except the Wasp. Even ran one or two.

Does anyone have any love for the Ok's?

Looks like an .039 lurking under the label on the NIB Cub. They're a bit more of a rare bird. I like the Cubs, but the ones I have either run well or not at all. There doesn't seem to be any halfway. As Ken mentioned, their lightness is an advantage.

rdw777 Sat Sep 03, 2022 5:08 pm

I have two Cubs, .049 and .039…. The .049 I bought when the model mags were advertising them again in the mid - late 90’s…. Have never tried to start it… The .039 I got from the bay a couple of years ago and did try to start it, With no luck, Just a pop on sloppy prime but no pick up and go…Fuel was 24% and had a 5x3 prop…. The head has three gaskets and all were in place when trying to start…Since you brought it up Bob maybe a Cub experienced person here can help Very Happy

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It has an OS #7 plug in it… Is that a good plug for this engine?

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Also I noticed the spray bar was loose… It has two holes in it and was oriented with the holes parallel with the crankshaft as received…

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I can roll it around to this position as well… But may not be correct..

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I can’t see down the .049’s long stack to compare…

Any words of wisdom are appreciated,

Robert

GallopingGhostler Sat Sep 03, 2022 5:37 pm

Bob's photo of the R.H. McCoy's along side the OK's reminds me of my latest Testor purchase, a Blue Head .35 R/C version. It doesn't have much historical discussion, neither.

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Until I purchased it, I didn't know there were Blue Heads before the lightning bolt case (with protective tines in the exhaust for a ringed piston) were made. I haven't disassembled this one yet for cleaning and rehab. I heard that some of the B.H.'s had chromed cylinders, which would have overcome the problem of the soft iron (not Meehanite), which easily eroded if one didn't protect it with adequate Castor oil fuel and avoiding lean runs.

Anyway, didn't see Robert's post before I made my post, started re-editing, got that weird rotating circles with numbers on it, and Bob, your post then came through. Hit the back arrow in the browser, my changes are still there, weird.

rsv1cox Sat Sep 03, 2022 5:39 pm

I have no words of wisdom Robert, but I have run some. Nothing remarkable, but not much negative either. Started easy, but no Cox Babe Bee scream.

Historically not much discussion here about the OK Cubs? Ok_run11

It just doesn't speak to me like the Cox and Spitzy's do. Ken wasn't thrilled with the Spitzy's but i like them. Maybe it's the name, maybe the style.

Gathered up some of mine.

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Oldenginerod Sat Sep 03, 2022 5:53 pm

Spray bar hole should point straight down. Some have two holes side by side. In my discussions with Ted Brebeck years ago I'm pretty sure he suggested they point straight down the throat. The spray bar can be fixed in placed with epoxy or JB Weld. Epoxy's probably better because JB weld contains metalic grit which could get ingested. Only use one head gasket, and some suggest that you fill the glow plug threads with gasket maker to help improve compression.

GallopingGhostler Sat Sep 03, 2022 5:55 pm

Overall I gather that the OK's are torque engines like the pre-Schneurle Enya's. Max RPM is something of the order of around 12k, may be more, but less than Cox. Ken's observation of using a 6x4 seems to substantiate that. I have the later R version .061 reedie, gather that similarly, a 6x5, 6.5x4, 7x3 or 7x4 might do better work at those lower RPM's.

Like Ken said, the NVA's are not that great. Mine, I had difficulty getting consistent runs on both the tankless (or with optional aluminum tank screwed to back beam mount "B" and the plastic tank with Cox bulkhead mount pattern "A". They used a blunt needle and a weird split threaded collar over the spray bar threads that leaks like a sieve. You can't simply put a short piece of fuel line over the joint to seal the needle leaks. Anything is an improvement over that. In fact, I was wondering if I might be able to drive it out and Epoxy a Sure Start NVA in its place.

And agreed Rod, Robert's spray bar should have the hole pointed downward where not seen, on the suction side of the venturi throat. Did these have 2 holes instead of one like some of the Foxes, almost looks like it with Robert's. In that case, it needs to be rotated down with the holes equidistant of each other.

Ken Cook Sat Sep 03, 2022 6:58 pm

It's my understanding that the .061 with rear intake was meant for the Comet model line due to needing more power. Fox also made the .07 for Comet but there was a falling out and Comet proceeded to leave the RTF market of plastic planes. I own one of the .061's and it is a terrific runner. George, your thoughts are right in order with using a Sure Start assembly. I've done this many many times. I just put a little JB weld around the spraybar on the outside of the case . Just so you know, a Q-tip and rubbing alcohol thins JB weld and will immediately clean it off of anything. You can tool a nice clean fillet around the spraybar. Regular epoxy would also do the same.

OK in and around this time started to offer a glow head vs the adapter for 1/4-32 plugs. I've always found the glow head to work well over the other.

As for OS plugs, it becomes very confusing for a few reasons. First reason is that OS plugs are unlike ANY other plug due to their length. This means that the plug length is going to alter the timing and I have experienced this more in larger stunt engines than with small 1/2A engines. That being said, your plug choice is going to be determined by your fuel choice. Seeing that the OK engines are crude, I highly recommend running them with a bit more oil content, this means that I would prefer a hotter plug. The OS #7 is a medium hot plug, it would more than likely work fine but it's designed for nitro contents probably 12% on up to nearing 20+ whereas you would then want a colder plug if the plug blows from use.

OS formerly used a letter designation for their plugs followed by a number. I believe the former #7 was known as a A5 where the hotter plug was a A3. You really have to try them and one can't just offer out what to use without trying it first so I would venture to say the #7 would work fine.

Mark Boesen Sun Sep 04, 2022 12:01 am

Rumor is that Bill Atwood designed the reed for the Cub .06 (aka .058, & .059) which does kinda hold water as Herkimer had no mechanical engineers at that time. They also had a much better needle assembly. These engines came after the Fox designed the Comet .07.

Comet was done manufacturing RTF's by '63, about the same time Herkimer stopped production of engines.

The Cubs you see in bags were sold by the grandson in the 80's-90's.

The Cub glowhead was intro'd in '58 on the P-40 and was designed to fit the Cox '56 cylinder, earlier Cub heads will fit the pre '56 Cox cylinder.

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Mark Boesen Sun Sep 04, 2022 12:09 am

This was done by Bill Mohrbacher several years ago.

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getback Sun Sep 04, 2022 7:28 am

I know I almost didn't get the red tank 0.49 new to run , i had never ran one and thought well its new what more could you ask for ?!?!? Anyway did run not that impressed , you have to pretty much flood it to get it to take fuel and keep running of coarse i feel I flipped it enough to break it end by then lol!

Maybe $200 isn't out of line to bad after watching this auction

Historically not much discussion here about the OK Cubs? Screen96

Nice collection Mark they are pretty ! This Site Rocks!

Mark Boesen Sun Sep 04, 2022 1:26 pm

Quality control was really hit or miss with Cubs, i think the really early ones and the early 60's reeds are decent, but there's a ton of them on the market that were put together from barrels of parts left over. Years ago i took a new looking 049A with a good pop and carefully broke it in (heavy castor fuel) only to have it wear out after 3-4 flights on a baby ringmaster.
We take Cox engines (Temp-trol) for granted, but they just about always ran great and were heads and shoulder above the other manufactures.

GallopingGhostler Sun Sep 04, 2022 2:40 pm

Mark Boesen wrote:We take Cox engines (Temp-trol) for granted, but they just about always ran great and were heads and shoulder above the other manufactures.

May be with the exception of the Queen Bee, there hasn't been a Cox that I didn't like. They were always ready to run after a couple tank fulls, always started up without issues. After crashes, a lot of times I'd wash away the grime with a shot of fuel, change prop if need be, then re-run them without problems.

Lately out of curiosity and before these were considered "collectables", I bought a few Cubs just to try them out. That is when I discovered the erratic needle valve issues not easily solvable. Coxes on the other hand had no needling issues.

rsv1cox Sun Sep 04, 2022 3:08 pm

Funny how a flea market phone call from my son can stimulate a thread that we all benefit from.

I printed out Bill's picture to keep, nice having the Ok's in one place.

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And picked out one of the neglected critters to mount. What! No compression. Peered through the exhaust ports and noticed the con rod poking it's head up. Second one like that in two days. What's the world coming to. Smile

Thought that maybe the last batch of wrenches contained an Ok wrench, but sadly no, neither fit.
Oh yes, a number 2 screw will not fit in the engines radial mount, 2/56 only.

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I would like to experiment with that diesel out front. Got a couple of them.

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rdw777 Sun Sep 04, 2022 4:49 pm

Thanks guys for the advice on the .039… I will apply those and see if I can get it to run…

Interesting information on the glow heads…. I have a working #302 Cox head I got in a parts lot… (has the smaller diameter threads)…. It threads onto the .039 just right… Doubt I will use it though ….

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Ken Cook Sun Sep 04, 2022 4:54 pm

The OK diesels actually run very well. George, I don't know if you still have that Queen Bee, did you ever try a TD .09 plug on it? A Kamtechnik turbo plug adapter would also work . I was pleasantly impressed with the TD .09 plug on mine

Mark Boesen Sun Sep 04, 2022 5:02 pm

Here's a couple of prized engines...new old stock engines from Herkimer NY, still coated in cosmoline, more than likely made for Comet.

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GallopingGhostler Sun Sep 04, 2022 6:37 pm

Ken Cook wrote:George, I don't know if you still have that Queen Bee, did you ever try a TD .09 plug on it? A Kamtechnik turbo plug adapter would also work . I was pleasantly impressed with the TD .09 plug on mine

Ken, no, I haven't tried a Tee Dee head on it yet. All of the other Cox engines, I simply followed the instructions, fueled up, lit up, it fired up. This one, the plug it came with apparently wasn't anything spectacular. Given the oddity of it and a heavy bugger at that requiring a long engine mount, with so many other engines that outshine it, it basically sat in the box these past 25 or so years. Then to add to the cruelty, when I brought it out again, the plastic carb mount bolt splines split, requiring replacing the carb venturi throat end. Apparently the black plastic isn't as sturdy as Delrin. Fortunately, part was still available from Ex Model Engines.

I may one of these days add it to the For Sale list in this forum. All the other Cox engines are basically bullet proof.

Oldenginerod Mon Sep 05, 2022 3:38 am

rdw777 wrote:Thanks guys for the advice on the .039… I will apply those and see if I can get it to run…

Interesting information on the glow heads…. I have a working #302 Cox head I got in a parts lot… (has the smaller diameter threads)…. It threads onto the .039 just right… Doubt I will use it though ….

The problem with the #302 head and the Cub heads which take the plug is that they seal at the top of the cylinder, not part-way down the bore like the later Cox and Cub heads do. The threads provide extra air-space at the top of the cylinder, soaking up a fair bit of compression. I guess it's the same theory as the standard Cox glow plug adaptor which has a similar problem, but to nowhere near the same extent as the larger diameter head.

EXModelEngines Mon Sep 05, 2022 2:04 pm

We've got a bunch of OK Cub 049 / Comet OK engines that I planned to list in our eBay store since I wasn't sure there was much interest in these types here, but should there be some interest we can post directly in the for sale area.

GallopingGhostler Tue Sep 06, 2022 2:23 am

EXModelEngines wrote:We've got a bunch of OK Cub 049 / Comet OK engines that I planned to list in our eBay store since I wasn't sure there was much interest in these types here, but should there be some interest we can post directly in the for sale area.

I guess you could post for maybe 10 days or link to your store to buy direct. Then list on the 'net?

EXModelEngines Tue Sep 06, 2022 6:28 pm

GallopingGhostler wrote:
EXModelEngines wrote:We've got a bunch of OK Cub 049 / Comet OK engines that I planned to list in our eBay store since I wasn't sure there was much interest in these types here, but should there be some interest we can post directly in the for sale area.
I guess you could post for maybe 10 days or link to your store to buy direct. Then list on the 'net?

Sure - I'll make a note to do this with the next batch. These are probably $20 - $30 engines. Used but in good shape.

OVERLORD Wed Sep 07, 2022 3:49 pm

I don't have an OK Cub engine and never owned one. On the other hand, I have a few OK Herkimer HO streamliner aluminium coaches. Most of them are sold in kit form but ready made models were also available. I have scale 80' coaches for my NYC Dreyfus Hudson and some 60' shorties for my PRR GG1. A few pictures:

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I think their quality is unequalled and all the parts are a perfect fit. I also have some under carriage detail kits.

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rsv1cox Wed Sep 07, 2022 4:59 pm

It seems like I remember one of them Lieven. Smile

They did make some really good stuff for the model railfan.

Winters coming, may be time to shift gears.

Bob

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