The OK Cub .060/.059

GWILLIEFOX Wed Jan 10, 2018 10:12 am

Since the Cub .06 came up, I thought I would post this tome. Herkimer was the original engine supplier to Comet. The Comet RTFs used beam mount Cub .049Bs, .074s in a few cases like the Hornet and Lebond cars, and later the tank mount .049A. Interestingly, the Cub 049A used the same mount pattern as the Cox Babe Bee (that used the same bolt pattern as the Space Bug). And when the Comet-Fox came out, it had the same tank bolt pattern as the .049A!

The Cubs weren't really powerful enough, so Comet went to the Comet-Fox .07. The Fox was designed with beam mounts so it could be used in either tank mount or beam mount applications. Comet used both styles.

For whatever reason, Fox fell out of favor and Herkimer again supplied engines to Comet, this time the reed valve .060. This engine, with its increased displacement and glow head, might have been the best small Cub ever made according to John Krickel.
The glow head as we all know now is THE way to gain power ( or the Nelson setup). When OK was going out of the engine business, they sold off many .060s as .059s, but they were the same engine.

The Cub .049s had a 0.420" x .360" bore and stroke, the .060 .420" x .415". Herkimer modified the .049B case to add a flange for tank mounting. The B case and the A case were also modified to have higher (longer) cylinder mounts to accommodate the longer stroke, had the front intake location cast shut, and had a new rear cover design with the built-in reed valve.

The cylinder was also made longer and the exhaust ports made wider. A longer connecting rod was needed; a rather chintzy socket crimp was used. The case had a milled relief to clear the rod and a blued steel washer was placed over the crankpin to keep the rod from rubbing the front of the reed valve mount.

These engines can be found in a great variety of combinations. Plain unmodified nose, nose modified for uninstalled starter, various starters installed, with and without beam mounts, with all tank lugs left on for tank mounting (Tri-Pacer, Regulus), some or all tank lungs clipped off for beam mounting (Horner, P51, Warhawk).

Hope this is interesting to you Cox folks. At least you can claim the tank mount!

Thanks to John Krickel wherever he may be for his .049 newsletter. And to Dave Evans for helping me complete my Cub collection!

Mark Boesen Wed Jan 10, 2018 10:22 am

Thanks for posting, love it!
The early head fits the pre '56 Cox cyl and later Herkimer glowhead fits the later Cox.
Lol, there's claims Bill Atwood did the design work for the reedie .060, freelancing while he working for Cox on Tee Dees.

Mark Boesen Wed Jan 10, 2018 10:24 am

Thanks for posting, love it!

John was hanging out in Atlanta area, had a nice visit with him several years ago.

roddie Wed Jan 10, 2018 12:16 pm

GWILLIEFOX wrote:

For whatever reason, Fox fell out of favor and Herkimer again supplied engines to Comet, this time the reed valve .060. This engine, with its increased displacement and glow head, might have been the best small Cub ever made according to John Krickel.
The glow head as we all know now is THE way to gain power ( or the Nelson setup). When OK was going out of the engine business, they sold off many .060s as .059s, but they were the same engine.

The Cub .049s had a 0.420" x .360" bore and stroke, the .060 .420" x .415". Herkimer modified the .049B case to add a flange for tank mounting. The B case and the A case were also modified to have higher (longer) cylinder mounts to accommodate the longer stroke, had the front intake location cast shut, and had a new rear cover design with the built-in reed valve.

These engines can be found in a great variety of combinations. Plain unmodified nose, nose modified for uninstalled starter, various starters installed, with and without beam mounts, with all tank lugs left on for tank mounting (Tri-Pacer, Regulus), some or all tank lungs clipped off for beam mounting (Horner, P51, Warhawk).

Hope this is interesting to you Cox folks. At least you can claim the tank mount!

Thanks to John Krickel wherever he may be for his .049 newsletter. And to Dave Evans for helping me complete my Cub collection!

I believe I have the same engine/tank as in your photo; top left.. except mine has a prop-driver. It was given to me last Summer in a boxful of assorted parts-engines from a fella down the road from me. Ken Cook actually spotted it when I originally posted getting the box of engines.

See the photos below..

It's got some dings and is missing one tank-screw.. but has excellent compression. I shouldn't assume that all is complete inside the tank.. because I haven't had it apart.

roddie Fri Apr 13, 2018 4:09 pm

I thought I'd give my OK Cub engine(s) some love today. The .060 (reed-valve) and .049A (frt. rotary-valve) both had some tank-issues as received.

The .060 was missing one out of three screws. The screws are 2-56 round-head machine screws that are approx. 11/16" long. I had several 3/4" long screws.. and decided to swap them all out.

As you can see in the last photo; the screws are 1/16" longer.. and stick-out a bit. I'm not concerned about that. My concerns are the reed-holder/rear-cover (looks like a back-plate) and needle-valve.. which are locked-up. I can probably heat-up the case to help remove the rear-cover.. but the tank (being plastic) worries me. I put some penetrating-oil on the needle-threads.. and will just let it sit and soak.. but don't know what else to try. I assume that there's a metal spray-bar pressed-in.. but maybe there isn't?

The .049A's tank had four Cox-type 2-56 fillister-head screws from a 8cc tank, that were threaded "part-way" in. They are MUCH too long. The 12 o'clock screw-position is in-line with the base of the engine-cylinder. That screw must be the correct length.. so I used one of the three; removed from the .060 engine (same 11/16" length..) to install in that location. I used the 3/4" length screws in the other three locations.

Again; the last photo shows the screws being 1/16" longer than original.

NOTE: Both of these engines use 5-40 prop-screws, as the Cox .049/.051 engines do.

I don't need to run them anytime soon.. but figured I should do a little work to them.. seeing that I had screws that would fit. Both engines turn-over with decent compression.

Oldenginerod Fri Apr 13, 2018 4:29 pm

Roddie. I have found the brass insert which the needle valve screws into can be fairly easily prised out from the plastic tank. You can probably firmly grip the needle in a vise and carefully pull on the tank. If you do, just ensure that your re-insert it with the hole in the side of the tube aligned with the hole in the tank.

As for the .049A tank screws, you do need to be careful with the upper screw as it can press against the base of the cylinder and distort it causing a tight spot as the engine is turned over. It needs to be exactly the correct length. I've even had original correct screws do it due to the tank being compressed by overtightening.

NEW222 Fri Apr 13, 2018 4:46 pm

Nice little Cubbies there. I kinda like the look of the clear/white fuel tanks. Would be nice for a quick reference to how much fuel is in it.

roddie Sat Apr 14, 2018 2:42 pm

Oldenginerod wrote:Roddie. I have found the brass insert which the needle valve screws into can be fairly easily prised out from the plastic tank. You can probably firmly grip the needle in a vise and carefully pull on the tank. If you do, just ensure that your re-insert it with the hole in the side of the tube aligned with the hole in the tank.

As for the .049A tank screws, you do need to be careful with the upper screw as it can press against the base of the cylinder and distort it causing a tight spot as the engine is turned over. It needs to be exactly the correct length. I've even had original correct screws do it due to the tank being compressed by overtightening.

Thanks for those tips Rod. Lots of good info and photos here by Bill M. too.

Regarding the needle; I chose to grab-onto the knob with my small locking-pliers, and loosen it.

It's been cleaned and reinstalled with light-oil. I removed the black Neoprene fuel pick-up line to find it surprisingly flexible.

I managed to remove the back-plate/reed-holder, by putting a small rectangular piece of .060" aluminum in a bench-vise, with just a slight "lip" sticking-up above the jaws.. enough to engage the slots. I applied downward pressure on the engine while turning it, which freed it up.

The reed looks "creased" (no good) to me.

ticomareado Sat Apr 14, 2018 6:10 pm

One of most informative Cub treads to come down the pike. Thanks guys. Nothing for me to contribute except:

"For whatever reason, Fox fell out of favor and Herkimer again supplied engines to Comet, this time the reed valve .060. "

The 'whatever reason' was that Comet Models wasn't paying its invoices from Fox. It would be interesting to know if Comet stuck Herkimer on the .060s.

GWILLIEFOX Sun Apr 15, 2018 6:36 am

ticomareado wrote:One of most informative Cub treads to come down the pike. Thanks guys. Nothing for me to contribute except:

"For whatever reason, Fox fell out of favor and Herkimer again supplied engines to Comet, this time the reed valve .060. "

The 'whatever reason' was that Comet Models wasn't paying its invoices from Fox. It would be interesting to know if Comet stuck Herkimer on the .060s.

Boy Tim, I've asked around for years about the Fox-Comet situation. Nice to know the reason. Frank Anderson (Andersons Bluebook) told me Duke made a raid on Comet to retrieve. 07 engines and parts. These engines became the Fox "Compact Stunt Motor". Mark published the .07 story. Ted Brebeck said Comet defaulted on Herkimer and returned thousands of 049 and 06/059 engines. Ted resold many of these ( the boue spinner Regulus engine quite common) and built many new Engines from parts.

Any more Comet info to share?

ticomareado Thu Apr 16, 2020 7:23 pm

Now I really do miss Gwillie. Maybe someone else (Boesen??)can help. This Ebay win came in today:

https://www.ebay.com/itm/1959-OK-CUB-049B-Stunt-Control-Line-and-Free-Flight-w-original-Box-/274328747247?nma=true&si=1hZAPNcovFOisKGTSp%252FoSsjpeqc%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557

As you can all see, it is not an .049B. The starter it has does not match any in this thread's photo gallery and it is wound up tight as a tick with no way to release the tension on the internal spring. The engine internals are free to move. The thing looks like it should operate like a Wen Mac Rotomatic starter except that it uses a wire spring instead of a flat spring steel spring. I'm afraid to attempt a disassembly.

Ken Cook Thu Apr 16, 2020 8:30 pm

Victor, I believe I have that engine which is a .059. What I find interesting here is that you now show me what my engine is missing which is the up front winder? This engine offers decent power for a old timer. With all the discussion of OK finally departing us, I contacted Ted. He said send me a picture of your engine and I will compile the parts needed to make it work. Sure enough, parts arrived in the mail. I couldn't even thank him as he took down the site and his e-mail. My engine is running and I'm real happy with it. I don't even care if I ever fly it. I just enjoy it.

roddie Mon Oct 30, 2023 9:59 pm

Remembering Bill Mohrbacher (GWILLIEFOX). I miss your contributions here Bill.

I gave my .060 a little more love tonight. It wasn't really planned. I was just looking through a box of loose engines.. and saw it there waiting to be paid attention to.

The last maintenance done was to remove the reed-holder assy. to examine. The reed looked creased and I didn't do much more with it until tonight.

There's a "circlip" to hold the reed against the mouth of the venturi like Cox uses.. except it's smaller than a Cox .049 circlip. The reed housing is .350" diameter and has a groove for the circlip to seat into.

I have to replace the reed. I'm wondering if there's a chance that a Cox Pee Wee .020 reed will fit.. (and the circlip for that matter). I don't own a Pee Wee to be able to measure its reed-housing diameter.

The Cub's reed is .0025" steel. Maybe I can cut the legs shorter on a Cox copper-star reed to fit the .350" diameter Cub housing. Huh...

The needle is in good shape... but I decided to apply the "silicone tubing seal" with flat-washer below the spring.

I'm not sure if there's supposed to be a "little mesh screen" over the air-intake.. but I won't try to run the engine without some type of air-filter.

GallopingGhostler Mon Oct 30, 2023 11:08 pm

Life is not perfect. I'm wondering if the reed can be salvaged by gently stroking the top side with a smooth tip of something like an edge of a screwdriver with the backside of a spoon as the supporting anvil. Maybe you can burnish out the creases on the reed sufficiently to flatten it and make it properly seal again.

Other option may be manufacture a reed from the mylar of a computer floppy disk.

rdw777 Tue Oct 31, 2023 6:31 am

Roddie, A PeeWee metal reed is .335 across…. The PW reed housing is .345 dia…..
PW circlclip wire dia. is .018 to .025 depending on vintage

The PW’s is close but maybe a little small…. Nothing to loose on trying to salvage your old one…. I like George’s idea with the spoon but use it as the burnishing tool with the reed on a piece of smooth hardwood or glass….Just roll it across instead of pushing so it doesn’t snag and roll up…. Maybe a little oil on the glass to help stick it down…

One more thought on metal reeds, I try to never handle them with bare fingers…. I have a little tool that is simply a straight pin in a bamboo stick…. Dip the tip in castor and the reed will stick to it just fine… Then you can safely move it around as needed…

roddie Tue Oct 31, 2023 8:18 am

GallopingGhostler wrote:Life is not perfect. I'm wondering if the reed can be salvaged by gently stroking the top side with a smooth tip of something like an edge of a screwdriver with the backside of a spoon as the supporting anvil. Maybe you can burnish out the creases on the reed sufficiently to flatten it and make it properly seal again.

Other option may be manufacture a reed from the mylar of a computer floppy disk.

I have to wonder what happened to this reed.. The tank-side of the reed-housing has a small "gouge" at the opening of the venturi. Someone may have stuck a small screwdriver in there.. and possibly poked at the reed. On closer inspection; it looks like a dent.. rather than a crease. The reed "seat" looks OK.

Yes.. making a reed is something I have done more than once with success.. and thought that I might try that.

roddie Tue Oct 31, 2023 7:15 pm

rdw777 wrote:Roddie, A PeeWee metal reed is .335 across…. The PW reed housing is .345 dia…..
PW circlclip wire dia. is .018 to .025 depending on vintage

The PW’s is close but maybe a little small…. Nothing to loose on trying to salvage your old one…. I like George’s idea with the spoon but use it as the burnishing tool with the reed on a piece of smooth hardwood or glass….Just roll it across instead of pushing so it doesn’t snag and roll up…. Maybe a little oil on the glass to help stick it down…

One more thought on metal reeds, I try to never handle them with bare fingers…. I have a little tool that is simply a straight pin in a bamboo stick…. Dip the tip in castor and the reed will stick to it just fine… Then you can safely move it around as needed…

Hi Robert, I appreciate the measurements! Thanks!! I remembered that I received a "printed" Cox .020 reed-holder/carb. with a Mylar-star reed, circlip, gasket and screws and also a Goldberg-style engine mount for the Cox 290 Product Engine; printed and assembled by JasonWI as a prize for my entry in the CEF "Cars are the Stars" contest.

Cox Mylar reeds I've found to measure a consistent .005" thickness.. but I didn't remove the one in the backplate to measure it.

The Cub's reed-housing and circlip are so close to the Cox Pee Wee size. I'm thinking that the circlips might be a standard size that was used on both engines.. Huh...

If so; the reeds would likely be the same size.

I'd like to try to make an oblong reed like the Cox current generation and see if it will work in the Cub. This Cub's reed-design has protruding "tabs" that locate into notches in the housing, preventing any radial movement. The Cox and Testors reeds can and do rotate below their circlips. I wonder if that would make a difference in the Cub.. Huh...

I tend to doubt it.

rdw777 Wed Nov 01, 2023 11:08 am

You bet Roddie, I had one taken apart so it was no problem to get the measurements…. Do you have any floppy disk material?….Before I retired I talked the IT guys out of one….I’ll send you a piece if you want to try it….. It’s about .001 thick or just a shade over…

roddie Wed Nov 01, 2023 11:32 am

I'm a creature of habit.. and one of my habits is keeping things in "zip-seal" clear plastic bags. I do this especially with model engines whether complete.. or broken-down into various stages of assembly. I'll generally use a "quart size" freezer-bag as the main bag.. and I have a stock of smaller bags for parts to be kept separate within the main bag. I write dated notes on index cards which go in a separate bag to help keep them clean/legible.

Here's my OK .060's bag..

It helps me keep track of stuff. Airplanes get "gallon size" freezer bags while being built.. and also for future notations/mods-changes/parts-swaps etc. along the way. OCD? yes..... very. Shocked

Regarding a propeller for the .060; I'm going to try a MA/Windsor 6 X 3. The engine's prop driver has a .180" diameter boss which protrudes approx. .062" into the backside of a propeller's hub-hole. The MA prop's hub-hole is .130" diameter on the front/face and tapers larger at the backside. All of my Cox propellers in the 5-6"d. range have .130" hub-holes front-to-back.. and I didn't want to counter-bore the back of one to fit this engine..

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